It was about 2 weeks later when I'd get to hang out with Caitlyn again. This time I wouldn't have to babysit her, but instead I'd get to take her out to our local mall all by ourselves. I didn't think her parents would allow for her to go alone with me, but I guess since I've babysat her for so long without any issues they figured it was okay.

I was wearing the normal jeans with a random anime t-shirt as I had mom drive me over to her house. Once we got there, I went to go get her, knocking on the front door as she answered.

Brandon: "ready for our big day at the mall?"

Caitlyn: "of course I am, because you'll be with me!"

I smiled and we walked back to my mom's car with her, She was so cute looking today. She was wearing a pink skirt with a nice little hello kitty hoodie on, her diaper slightly peaking out from under her skirt as she got into the back seat with me.

My mom started driving as she asked chatted with us for a while on the way there.

Mom: "so, Caitlyn you must really like it when Brandon babysits you I bet?"

Caitlyn: "y-yeah, he's pretty fun to be around and do stuff with."

Mom: "oh, and what kind of stuff do you guys do exactly?"

Caitlyn: "W-we play together, he's reaaally good at that."

Brandon: "uh yeah, we play plenty of 'games.'"

Mom: *laughs* "well as long as you enjoy hanging out with my son and he makes you have fun!"

Before we had known it, we made it to the mall and my mom wished us a fun time as she reminded me to text her when we're done. We got out of the car and began walking into the mall together, as I thought of why we were here. She was wanting to buy some new clothes that she's been looking forward to buying for a while.

I opened the glass door to the mall as it was a bit crowded inside, making our way in the building. She lead the way to which stores she wanted to shop at first, we stopped by a store called Abercrombie and she started looking around at some cute little tween clothing. She picked up a few clothes but nothing too exciting that she wanted, before we moved on to the next store called Justice.

She looked around some more and found some cute outfits that she picked out and we paid for them before again moving on to another store, I was starting to get bored even though I was with my now little girlfriend. We finally stopped by another tween store called Forever 21, as she was looking around at the clothing, I noticed I was the only guy in the whole store.

The workers giggled to themselves as they watched us shop, it was kind of embarrassing but I figured in their eyes, we looked like we were brother and sister. Which would just mean that I was dragged along to help my little sister shop, but in reality it was actually that I was shopping with my little underage girlfriend.

While she picked out a few more outfits, she spoke up a bit.

Caitlyn: "would you help me choose out some panties that you think would look good on me?"

Brandon: "w-wait.. what? you don't even wear underwear though.."

Caitlyn: "it's okay, I could always buy them in a size or two bigger and put them on over my diapers."

Brandon: "now that's kind of hot.. okay, let's go pick out some panties for ya."

She giggled as she lead me over to the underwear section, where she grabbed a few different pairs of panties, holding them up to me.

Caitlyn: "what about these my little pony ones?"

Brandon: "those are pretty cute"

Caitlyn: "or what about these blue striped ones?"

Brandon: "I like those too, hey how about you grab these cute little bear design ones?"

Caitlyn: "sure! I want to go try them on and make sure they fit."

Brandon: "sure thing, let's head over to the dressing room."

We headed over to the dressing room which was a bit out of sight from the counter, where the workers were standing and still giggling to themselves as they watched me just help her shop for panties. Caitlyn opened up the changing room door and headed inside, as I was standing outside of it.

It wasn't a long wait before she waved for me to come into the dressing room with her, as I double checked that no one was watching us. I stepped into the changing room as she was lifting her hello kitty hoodie and t-shirt off her flat chest, her perky pink nipples greeting me, followed by her unzipping her skirt which fell to the ground.

This left her standing there before me in just her diaper, as she pulled her diaper down to her feet, giving me a nice view of her tight little pink pussy lips.

Brandon: "god damn it, you're so fucking sexy Caitlyn."

Caitlyn: *giggles* "t-thanks."

She reached for a pair of the brief panties that has a cute little bear print on the back of them, sliding them up to her waist just below her belly button. They fully covered the back side of her butt cheeks, as she did a cute little pose for me in them, asking me if I liked how she looked in them.

Caitlyn: "do they look cute on me?"

Brandon: "I think you look cute in general baby."

My cock was diamond hard as I decided to show her just how she was making me feel. I unzipped my jeans and pulled my white briefs down as well, my big cock flipped upwards as she was amazed how hard I was. She giggled and walked over to me, before placing her small hands around my cock and slowly jerking me off, the foreskin moving along with the strokes.

She got down on her knees and opened her mouth, licking and starting to suck the tip of my cock. Slurping noises filled the room as she kept sucking and drooling all over my dick, spit and drool dripping from my cock onto the ground as some of it dripped from her chin.

While she was in the middle of sucking my cock, she popped my cock out of her mouth for a moment, looking up at me with a look of worry.

Caitlyn: "Brandon.. I feel like I've got to poop badly!"

Brandon: "really? here.. stand up real quick, I want to see this."

She was blushing with embarrassment, as she stood up and I turned her around with her back facing me. I watched her as she closed her eyes as she was letting out a few farting sounds. Her back end of her panties were filling up nicely with her poop, which was expanding the bottom of them outwards a bit as I could see them becoming stained slightly, poop was starting to try forcing it's way out the back of her panties.

I pulled the back waistband of her panties away from her body and looked inside to see that about 3/4 of the back of her panties was filled with poop. I began patting the bottom of her messy panties, trying to make it more messy as bit of poop started squishing out and onto the floor.

Brandon: "such a bad little girl.. pooping in your panties like that!"

Caitlyn: "I-I'm sorry for being so disgusting in front of you.."

Brandon: "I'm going to have to punish you for not acting like a big girl now, you know that right?"

Caitlyn: "P-please don't be too rough with me."

I pulled the bottom of her panties near her crotch aside, enough for me to fit my cock under there as I began thrusting my cock between her cute butt and messy panties. This caused for more poop to spill out onto my crotch and onto the floor as well. I grind-ed my cock around inside of her panties, as I could see that she was starting to slowly moan, she was enjoying this as much as I was.

I couldn't take it any longer and I felt my dick around within the mess of her panties, as I lined the tip of my cock up to her messy asshole. I pushed the tip of my cock into her asshole as she let out a yelp of pain, I covered her mouth for a moment in order to not let our voices get too loud.

Brandon: "does it feel just as good as our first time doing this?"

Caitlyn: "it feels so good Brandon.. f-fuck my tight asshole more."

I slowly worked my cock deeper into her tight asshole, her mess inside her panties was coating my shaft in poop, even more poop fell onto the floor as I was able to start fucking her a bit quicker now.

Caitlyn: "I love how big your cock feels inside of my asshole!"

Brandon: "I love you for letting me fuck such a tight hole in the first place baby!"

Within that moment I wrapped my arms around her belly and had one hand playing with her perky nipples that were hard. I continued sliding my messy cock deep into her, back and forth as I held on to her tightly. She turned her head enough for us to kiss each other and that's when I couldn't hold it any longer.

I unleashed a massive load of cum deep into her asshole as I slowly pulled my now messy cock out from under her dirty panties. She climaxed shortly before I came, making the front of her panties soaking wet. She stood there with a look of pleasure on her face and we kissed each other for a while, before deciding that we should hurry up and get dressed.

I pulled my briefs and pants up, just letting my poop covered cock sit in my underwear without cleaning it, since there wasn't any way to do that in here.

Brandon: "Caitlyn you're going to have to buy those messy panties now and let the manager know what happened to them."

Caitlyn: "B-but.. it's embarrassing!"

Brandon: "I'm sorry baby, but we can't just tell them we were fucking in here and that you shit yourself.

Caitlyn: *sigh* "f-fine.."

She was blushing but had a mix of anger on her face as well, as she pulled her skirt back on zipping it up around her now messy dirty panties, next she put her t-shirt and hoodie back on to cover her perky nipples. I picked her clean diaper up from the ground and put it in the nearby trashcan on our way out of the changing room.

We walked up to the counter to check out what clothing she wanted to buy and I mentioned that we need to speak with the manager. The clerk working told me that it was nice of me to help shop with my little sister, as she scanned her clothing. The manager walked over to us, before speaking.

Manager: "hi there, what can I help you with today?"

Brandon: "go on Caitlyn, tell the nice lady what happened."

Caitlyn: "I-I.. was trying on a pair of panties.. w-when I pooped myself, I would like to buy them still."

Manager: "oh sweetie! it's okay, things happen all the time.. are you still wearing them?"

Caitlyn: "y-yes.."

The manager offered to let her get cleaned up in the back room and wear one of the new pair of panties she bought instead. The manager took her back and once Caitlyn took the messy panties off, she stuck it into a plastic bag to keep the smell from being noticed. It wasn't long before Caitlyn returned as I had all her clothing bags in my hands.

I could tell she was all cleaned up nicely now since she smelled much better than before. I thanked the manager for the help and understanding as we walking out of the store and I texted my mom that we're ready to be picked up now.

All in all, going to the mall with my little underage girlfriend is pretty fun!