It was two in the afternoon and Bart Simpson was alone in the living room Playing a generic Zombie game, There was nothing else to do, his parents were out on some stupid romantic afternoon and he had everything all to himself ah what a bliss it was.

"Take that you stupid bloated zombie haha!"

While he was having fun Bart starts to hear a soft crying coming from the kitchen, normally he couldn't care less about it while playing his dear game but something told him that it was important, so putting the game aside (yeah he did that) his curiosity took the best and walked to peek.

From the corner of the wall, he saw his sister Lisa Simpson with her head down on the kitchen table looking unhappy...because she was crying. Lisa was fourteen years old but for some reason, she always looked older than Bart, one of the reasons was that she looked taller than him who was sixteen, the second reason? well...he would never admit this in front of her but she had a BIG BUTT" it was just so big, tight, jiggling, soft (in his dreams) he was surprised the chair could take her.

'I should go talk to her I guess'

Walking next to his sister he tries to make his best friendly smile and starts talking.

"Hey Lisa, why are you crying? did people start calling you starfish because of your hair?" Anddddd he made fun of her...damn his inability to talk with big booty girls.

The Nerd girl is startled by the voice of her brother turning around to look at him, quickly wiping her face as nothing happened.

"W-what are you doing here?" She asked

"I live here? also, you were so into crying that you stopped to realize you were not alone" The cocky teen said.

"Whatever goes away!" She said turning her face away from him.

"Cmon Lisa, why don't you tell me about what is troubling you?" He asked.

"And you actually care about how I feel?"

"Ugh...calm down just because I don't praise you like a goddess doesn't mean I won't look out for you" He said trying to look firm but still himself.

The poor girl just sighs "Everyone in the school is making fun of me because of my weight, they keep calling me fat because my ass is so big"

Lisa said then getting up from the chair and turning around showing her Big bootylicious booty that was being held by a pair of blue leggings while pointing to it to prove her point. Bart stares at it with a serious face like he was considering this but in reality, he was…

'Holy shit! How can she have such a nice ass? I wonder how big it would become when she turns eighteen...hmmm maybe I can take this to my advantage, Lisa is smart but she always took less interest in Sex ed' With a sigh himself he looks at Lisa's face "Look Lisa having a big but doesn't mean your fat or any less attractive"

"It doesn't?" She said the answer was not so easy for her to accept.

"What you have are sexy curves, weight in the right places making you very attractive and the other girls are jealous of you because they are not as beautiful as you" He said with honesty which his heart skips a beat.

Lisa just stares at Bart in disbelief that he actually said that, was the brother she thought was just a childish boy actually caring for her.

"Thanks...this makes me feel better, also you think I am attractive?" She asked with a smile.

"Yeah...Yeah, I do,y-you know what girls with butts like you actually use them for? some dancing name Twerk" He said trying to make his move.

"Twerking? hm...interesting what is it about?" Lisa asked

'To convince Lisa I gotta say more than just shaking your trunk, hmm let's see, she loves studies and culture so maybe…' "Twerking is a type of dance move, in which you squat and thrust you can also be referred to as booty shaking. The word was derived from merging the terms *Twist* and *Jerk* Others think the term comes from the dance saying "work it", while it has been a common move on the bounce scene in New Orleans, USA, for years"

"Really?" She was close now listening to it like it was class time.

"I-It's also a good way to fat burn and toner, and is pretty much guaranteed to give you a rear of the year, you will make all the girls jealous" He said, a little embarrassed.

"Whooooa" Lisa said actually impressed her brother to know this much about something.

'This girl is too...naive' He Sweatdropped

'Hey! I want to try that out" She said with glee

"What? right now? w-well I suppose we can do this...how about your room? mine is too messy and we can have more privacy since you need someone to look how you doing" He said now getting excited

"Hmm...yeah! makes sense, let's go now Bart" Lisa said while Bart was feeling lucky.

Lisa's room was spotless and organized, sure this is to be expected from the girl since she was the best at almost everything. Once there she looks up for something on her phone like she is searching for music to go with the tone but Bart tells her that maybe right now just a nice Beat was enough for her (all he needed was the nice view anyway)

"Nice, this beat is good, why don't you show your brother the moves?" He asked with a perverted smirk.

"Well don't expect much from me, this is my first time" She said

Even though Lisa said that the moment she moved away from Bart and closer to her bed her booty started to shake with energy, the beat and the wiggle from her glutes were one in perfect harmony shaking it up and down, pants were not enough because each time it wiggles you can clearly see it ripple like it was jello.

'W-what? that shake, that wiggle, how can she do it so smoothly?' His eyes go wide.

"Whoa, this is pretty fun! haha maybe if I do this!"

Lisa then starts moving her booty left, right, up, and down trying to make a new move, surely she does so now twerking her booty in the form of a number "8" by using her hips.

A tent starts to form on the boy's pants, seeing his sister's sexy booty shaking like that is enough to make his member throbbed with desire for that booty, man how he wanted to feel it on his hands, squeeze its softness like dough, and shove its face to just SNIFF! the scent.

"How about that Bart? Do you think I am good at t-" She said turning around but by doing so she gasps in surprise.

Bart facepalms himself mentally for not trying his best to somehow hide his boner in case it would be having this moment right now in which she would look at him with no warning.

"Bart...what is that on your shorts? did you hide something there?" She said pointing at his bulge.

'Does she seriously doesn't know what a boner is? man for someone so smart maybe she decided to not search much about sex' "Oh this? is just a...sign! yeah, a sign that a man is really happy to see another woman, it shows its excitement and eagerness to the females" He said, making up bullshit.

"Fascinating" She said, stopping her twerking to look closer to his bulge at the same time, getting on her knees which only makes Bart dick twitch.

"Can I see it without the shorts and undies?" Lisa asked

"WHAT? Why would you want that?" He asked surprise

"Because I can't help myself when my scientific side kicks in, I must research more about this" Lisa said with an obvious naivety at this subject,

'Maybe I can take advantage of this' "Ok I let you do whatever you want if you so curious but only if you allow me to do the same with you but...with your butt" He said with a smirk

"Eh? my butt? but why?"

"You're the only girl I know with a butt this big and I am also curious to see why big booty is so interesting for me" He said.

The girl thinks for a while about this deal, she never felt interested in a man's lower part before but right now it was like something was pushing her interest to it, maybe her hormones? and she blushed a little because of her brother's interest in her derriere.

"Ok deal" She said with a smile.

'Oh shit! She actually said yes? ohhhhhhohohoho yeahhhh' "Cool, let me get this out for you"

He said so removing his shorts revealing the underwear barely holding up the big bulge of a boner which makes Lisa gulp in anticipation for...some reason?

"Time to let little Bart out to play" He said, taking off his undies.

Lisa Gasps in surprise seeing what appears to be a pretty big yellow cock pulsing with energy and balls the size of tennis balls, how the boy hid all that on his shorts was a surprise and a mystery.

"Here you go Lisa, this is what your butt did to me" Bart said proudly of his dick size.

"I-Its so big and...throbbing" Lisa said with her eyes wide as plates.

"You wanna try touching?" He asks

"C-can I really?" Lisa asks, still looking at his penis.

"Sure! and after you do that you're gonna show me your butt later, I think this will be a good moment of knowledge for you" Bart said with a smirk.

The girl with still some naivety could not understand her urge of wanting to do 'things' with her brother's cock, it was like something inside her was asking to just embrace the new feeling of no control on her hormones.

Finally letting her logical part out of her brain Lisa proceeds to first touch Bart's penis with her left hand to feel how rugged it was.

'I-It's so warm and hard' She thought, biting her lip.

The brother is enjoying the view of how much interest Lisa demonstrates in his manhood and is holding his moaning for now. The girl with the starfish hair starts to stroke her brothers cock up and down with her soft hand, it was enough to make him moan in pleasure as it felt TOTALLY different when he was the one doing it to himself, that makes Lisa smile that she is making Bart act like that with just her hand, seeing how it works a faster pace is then put in and now Bart is getting a handjob by his own sister hand and ooooohhhhh the sinful pleasure was sinking on fast making him feel how good it felt to be doing something wrong.

'S-So good' He said with his mouth open like his dad would when he thinks about Donuts.

'This is surprisingly Fun, and the smell...even though it's so weird it makes me feel hot and hotter...what if i'

At that moment Bart feels his balls being grabbed by his sister hands giving him a quick yelp

"Whoa! easy there t-they sensitive" He said between moaning.

"Fascinating, so these are testicles huh? they are so malleable and squishy but I think it's where it causes more pain in a man if you hit it huh?" She said with an evil smirk.

Bart gulps for a moment feeling afraid that her sister has his balls on her hands and can take revenge on him for anything he has done before to her but she just laughs it off.

"Relax I am still going to give you what you wanted" She said making Bart relieved.

'That was arousing and terrifying' He thought

Lisa gets up and turns around starting to slowly remove the fabric of clothing that was hugging her buttcheek. For Bart, it was a good show to see every inch of skin flop out of those tight pants freeing her booty meat, after fighting with her jeans for a good time Lisa can take it off revealing her beautiful booty of marvelous proportions.

"Phew! remember me to buy bigger pants. Well, there it is, are you happy now?" Lisa asked

"I...It's so beautiful" Bart said, almost crying at the booty he was seeing.

"Eh? oh, c'mon n-no need to say it like that" She said blushing.

"PLEASE! GIVE ME A BUTTJOB" Bart begged.

"What? ahn...what is a buttjob?" Lisa asked curiously.

Bart inhales air and starts acting like he was teaching something" Is the act of a man sticking his penis in between a woman's ass and the woman squeezing her cheeks as the man humps"

"What? t-that was not on the deal, that sounds embarrassing and weird"

"Cmon Lisa, I know that you like touching my dick and balls, you are curious right? don't you wanna find out what happens to a penis when they hit max pleasure?" Bart said, grabbing his own penis and making a suggestion.

"W-well I think that maybe it would be educational?" Lisa thought for a moment.

*Two Minutes later*

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"Ahhhhhnn! ohhhhnn! hmmmm! my! oh yes yes yes! it's so warm" Lisa moaned.

"Ohhh fuckk! so soft!"

Lisa was on four in Bart's bed while the latter was behind her and rubbing his meat pole between her ass cheeks like a hamburger for two minutes so far. The moment Bart put his cock on that warm place was like his dick was enveloped by the world's softest material on the planet, the warmth and sexiness pushed him to a new height of an erection, and just went bananas humping her butt cleavage.

"L-Lisa I think I am about to cu-AHAHGHGN!" He can't even finish the sentence before making weird sounds.

The big booty girl feels an enormous amount of sperm come and spray all over her ass cheeks like a damn cannon of the white substance of sticky nature...it felt exhilarating.

"Yahnnnnnn! ohhhhnnn y-yes! hmmm all over me" She said clenching the bedsheets.

'Oh...oh man...this is the first time I came this much, it's way better than doing myself that's for sure'

"I would never guess all of this would feel so good, I learned a lot today Bart" Lisa said with a faint grin.

"Your welcome Lisa, but remember...don't try this with anyone else ok? ahn...i-it's not something you should try with strangers but only someone you know for a long time and you trust" Bart said

"Sounds fair" Lisa said.

"Now let's clean us up before mom gets home, or else she is gonna flip"

"Oh I love keeping secrets" Lisa said.

"Trust me...this is the biggest one so far" Bart said putting his shorts back up.

Now the two siblings had a special moment only meant for them...maybe?