Penny was not a jealous person, oh sure she gave Veronica Miller a black eye for necking JJ after he had asked Penny to Prom, but she was not blind, she saw the way JJ was being as enthusiastic as Veronica herself so she made sure to make things even and also gave JJ a black eye to match…bastards ended up marrying each other after highschool, lovely wedding, Penny cried at how beautiful Veronica looked.

So, in short, Penny is confident that she's not a jealous person, even when Kurt cheated on her she was upset about the break of trust (and of her heart) but not because someone else had 'taken' Kurt from her. Once a cheater, always a cheater, she cried for the lost time, for trusting in him.

When she started to take notice of Leonard and then he dropped her like a sack of moldy potatoes for Alicia (and Priya, and the girl that smiled at him giving him a cup of coffee, and that cougar lady that did jazzercise around the building block), well, she was disappointed, she had thought that Leonard was different but no, he was just like the rest, just better at hiding it. She had to sit him down and explain that to him, that no, it wasn't jealousy and that she deserved to be treated better and in a moment of genius that even Sheldon would be proud of she had declared to him ¨Even if we do end up going out, I would have to wait a year before we slept together¨. She tried to keep the hurt from her heart when he looked at her as if she was crazy and proclaimed they were better as friends. She did cry a little that night because she had been certain Leonard was different, that they were friends, what a mistake she almost made.

And thus, Penny can happily conclude that she's not a jealous person. So she's not sure where that feeling of hot and cold on her face, the shaking fists and the sudden stone in her gut is coming from. Because Penny, as established before, is not a jealous person. But that and other beliefs start shaking when she sees Sheldon being assaulted by that redheaded floozy. She still can't say the name Ramona without hissing and wow, okay, she's not jealous, she's just a very good friend that hated seeing her friend being pawed at. Besides, this was a fluke, a one time occurrence, those feelings will go away because this won't ever happen again Penny proudly thinks.

The next time it happens, Penny was having such a great day, she got the lead in a play! She couldn't wait to tell her guys, so she quickly went home, changed into her comfy Hello Kitty pajama shorts and a yellow tank top and put on her robe and entered 4a without knocking as usual and with a greeting that died in her throat.

You see, Penny was not a jealous person, she was 100% confident in that assessment so when she entered 4a and saw a brunette woman that looked as tall as Sheldon, built like a Victoria Secret model (wearing some pretty nice shoes) trying to kiss Sheldon in his spot while he resisted, well at that moment Penny had to reassess that stance because she was sure that the tingling in her arms, the feeling of sudden heartburn as well as the way her stomach was churning meant that either she was jealous or having a heart attack and she didn't know which one she would prefer at that moment. Putting that thought aside for a moment (she was not avoiding it, truly) and making a quick analysis of the current situation she came to some conclusions:
-Sheldon was in his spot and the brunette jezebel was in Penny's spot
-Leonard was in his chair looking very proud of himself (Penny decided right there and then that he was guilty of whatever was happening)
-Bombshell brunette had not noticed her yet
-Sheldon was actually losing the struggle
-Sheldon DID notice her entrance and looked at her in a way that makes Penny want to put this brunette hussy in the hospital
-Penny had to act NOW

While Penny wasn't a jealous person, she was a very athletic one so jumping over the coffee table she quickly put herself between Sheldon and this girl and holy crap on a cracker, the girl was strong. Finally getting enough leverage she was able to push the girl off from her Sheldon and in order to prevent her from trying to approach Sheldon again Penny did the only thing that made sense. She sat in Sheldon's lap while keeping her arms out warding her off.

Penny wanted to scream at this girl to stop, to get away and to leave the apartment but what came out was closer to ¨Whawhawhawhawhawahwahwa¨ not one of Penny's most eloquent moments but she hoped the intent was communicated.

Several things happened that made Penny aware of her position. First, Sheldon actually held her, not in a 'You're my shield now' kinda way but in a 'You're my teddy bear' kinda way, one of his arms went around her tummy and the other around her shoulders so Sheldon was basically trapping her against him. Second, Sheldon's hug (because there's no other way to call it) actually puts her flush against his chest and more importantly on top of Sheldon Jr if you catch her drift. Third, she still couldn't believe it so she shimmied a little on top of him and maybe that was a bad idea because she could feel Sheldon Jr react to her movement and grow to say hi. Fourth, Sheldon was hiding his face against her neck so she could feel his breathing against her and all of this made it very, very hard for Penny to concentrate on anything else.

¨PENNY!¨ Of course Leonard would be the one to focus on the fact that she was on Sheldon's lap and not on the fact that his roommate had been assaulted not 2 feet away. Leonard stood up and was trying his best to imitate a tomato as he glared at them, or maybe just at Sheldon, she couldn't actually tell.

¨Leonard, shush!¨ she knew that her usual bravado was somewhat diminished by Sheldon currently using her as a life-size teddy bear but the way Leonard flinched she hoped that it was enough, because Penny still had an undergrad brunette hussy to send home.

When she turned to lay it on the would-be assaulter Penny was confused, instead of the woman looking ready to brawl or being shocked or on the verge of tears she instead looked proud? What the hell…

Nevertheless, Penny had a job to do and by golly she would do it ¨Now, listen here! Dr. Cooper doesn't need your assistance or your manistrations-¨ Sheldon quietly intervened ¨Ministrations¨ and Penny quickly nodded and patted the arm around her tummy ¨That too!, so you can go back home and-¨ Penny trailed off as the other woman began to belly laugh with so much mirth that Penny just wanted to go over there and show her why she was the Junior Rodeo champion but all those violent thoughts disappeared in a moment when Leonard decided to interrupt again ¨That's his sister!¨.

We have established that Penny is not a jealous person but she was the type of person that was good at jumping to conclusions (and on Sheldon's lap a treacherous part of her mind added) but she was also good at dealing with unexpected situations but the relief of the situation might have made her a little too glad that Sheldon was not being assaulted by a stranger that she forgot exactly where she was and instead went into 'meeting a new friend' mode.

¨Oh my godI'm so sorry!, it's just that We've had to deal with some persistent undergrad students that can't take no for an answer and -oh- I'm Penny by the way the next door neighbor¨ and she offered her hand to Sheldon's sister (thank god for that) trying to smooth over the situation.

¨Oh darlin' you're precious! You were trying to protect Shelly, how adorable, I'm Missy darlin'.¨ this coming from anyone else would have made Penny get on the defensive because someone might be trying to bully Sheldon but his sister, Missy, had none of the teasing in her voice, she was truly happy that Sheldon (Shelly) had someone in his corner and was honestly happy to meet Penny. Missy shook Penny's hand and the both of them started to chat, about their lives, about Sheldon, about waitressing and it wasn't until she adjusted herself that she remembered exactly where she was, and that was because Sheldon Jr knocked on her door and ringed the buzzer, but it was fine, she was an actress, she could cover her moan with a cough which she almost immediately recognized was a bad move because coughing just made her body shake on top of Sheldon's lap and it was a bad angle (or very, very good her horny mind provided).

Penny decided that she might need to invest a little more in acting classes because Leonard suddenly squished his face in a way that made him seem eerily like his mother and left the apartment not without first slamming the door on his way out.

Thankfully Missy was someone that could read a room so with a quick ¨I'll go check on him.¨ she left right on the heels of Leonard, leaving her and Sheldon (and Sheldon Jr).

She patted Sheldon's arm ¨Sweetie, I think you can let me go now.¨ good, her voice didn't tremble.

¨Penny?¨ Sheldon looked around and down at her on his lap, like he couldn't understand how that had happened ¨Penny!¨ and then Sheldon stood up but he either didn't realize or didn't care that she was still on his lap and when he stood up suddenly like that something very interesting happened and that was that he pushed her with his hips and Sheldon Jr ringed her bell once again but this time someone answered and oh god it had been a while, she stood there bent over with one hand holding for dear life on the middle cushion while her legs tried to remember that they were in fact not jelly.

Penny had made up her mind, she was going to pretend nothing happened, this was normal, what's a little second base stealing between neighbors, she was going to go back home, take a long hot bath and NOT remember this evening while using her shower head and all of that flew right out the window when she turned to look at Sheldon.

Sheldon's eyes had always been the clearest shade of blue, electric and bright but now they were so dark that they might as well be the ocean itself. ¨Sheldon?¨ Her voice came out husky and it made Sheldon's eyes darken even further.

Penny was not a jealous person, but she was good at jumping to conclusions. And to Sheldon's lap, she kissed him and it was desperate and awkward but Sheldon quickly adapted and thank god for his beautiful brain because he was learning on the job and he was excellin to the point that she felt like jelly again and they were just kissing!

Of course that was the moment that Leonard and Missy decided to return but thankfully Missy is a no nonsense kind of girl and quickly dragged Leonard back out as he whined about how the universe was not fair ¨Have fun Penny!¨ Missy's voice ranged out. She should take Missy out for lunch in thanks, Penny thinks absentmindedly and then Sheldon bites her lip and Penny can't think of anything else.

Penny is not a jealous person but you better stay away from her Moonpie or she'll go Junior Rodeo on you.