A/N: One-shot that popped into my head last night as I was trying to go to sleep. So I cleaned it up today, and here it is.

Sheldon was distracted. People had constantly been bothering him at work, and he hadn't been able to spend time concentrating on the problem he was stuck on. And now that he was off work, and supposed to be back to his regular schedule, the problem he hadn't been able to concentrate on during work hours wouldn't leave his mind.

On the drive home, Leonard had been rambling about some unimportant project he was working on, but Sheldon hadn't quite been able to completely tune him out enough to successfully solve his problem. He felt like the answer was just on the edge of his brain (metaphorically speaking, of course), but he just couldn't quite reach it.

Things hadn't gotten any better when he'd gotten home, as five minutes after he got in Penny had burst through the door (without knocking, of course), and began rambling about her day. Normally, Sheldon didn't mind his aesthetically pleasing next door neighbor talking about her day, as he could tune it out and concentrate on whatever he pleased, but it just wasn't working today. And she also seemed rather more intent today on asking him questions, which he'd taken to just nodding his head and vaguely answering in the affirmative in hopes that she would stop asking him questions.

After about the tenth time Sheldon answered with a distracted nod and some form of a 'yes', Penny knew Sheldon wasn't paying her the least bit of attention. Several of her questions had been of the type that he normally would have launched into a ten minute dissertation on; and while she could grow tired of his lectures pretty quickly, a distracted Sheldon wasn't much fun, either.

As it was just her, Sheldon and Leonard that night, she decided to test just how distracted he really was. She knew Leonard wouldn't exactly be thrilled with her method of testing his distractedness, but hey, they'd broken up over a month ago, and as entitled as he acted sometimes, it really wasn't any of his business. Anyway, it was just a joke, it's not like she was serious.

"Hey Sheldon, want to have sex with me tonight?"

As she expected, Leonard's eyebrows shot through the roof. She supposed they rose a little higher when Sheldon just nodded his head and said, "Sure, whatever", but as she could no longer see them, she wasn't completely positive.

Welp, that definitely proved he wasn't paying the slightest bit of attention to her (or anyone, it wasn't like Penny thought she was the only one being ignored, he'd given Leonard the same mumbled nod earlier, as well). So she decided to up the ante.

"How about we start right now?"

"Yeah, sure, that's fine."

Not entirely sure why she was doing it, other than the fact that it was probably her only chance to ever do so, Penny flipped from her spot on the couch into his lap, and planted one right on his lips, her hands cupping his face so that he couldn't move (not that it was exactly necessary, as he completely froze when her lips touched his).

A second later, Penny rolled back into her spot and casually picked up the remote from off the table and flipped on the tv to reruns of 'Firefly'.

"I hope Firefly's okay with you guys," she said as the show started, settling back into the couch, acting as if nothing out of the ordinary had just happened.

Both Sheldon and Leonard were staring at her in complete shock.

"Oh, and by the way, you agreed to have sex with me tonight," she added nonchalantly.

Sheldon was no longer distracted. He hadn't solved his problem, but he certainly wasn't distracted anymore. As such, his mind was quickly able to assimilate what Penny had said after she had ceased invading his personal space. Well, the thing she'd said after "I hope Firefly's okay." That wasn't a problem; Firefly was always welcome. But the other thing was a slight problem. But before his brain had time to create the proper response, his mouth jumped in:

"I suppose it has been long enough since you've had a satisfying sexual encounter that even I seem like a reasonable option for fulfilling your needs."

Damn it, mouth! Penny's not going to be happy you know anything about her sex life.

"WHAT!?" A complete look of shock overtook her face. "I'll have you know I haven't had sex with anyone since Leonard, satisfying or otherwise!"

She wasn't exactly sure why she was telling Sheldon she hadn't slept with anyone since Leonard; it certainly wasn't to make Leonard happy. She didn't really care what he thought.

"I know."

She stared at him for a few seconds before it clicked. Leonard was still clueless.

As comprehension hit her, her face went from one of shock that Sheldon would know that she hadn't slept with anyone since Leonard, to one of shock that he would know Leonard hadn't exactly been 'satisfactory', as he put it, to one of shock that Sheldon had completely burned Leonard and based on the smug look on his face knew it.

Leonard still didn't.

Pulling her thoughts back together with great difficulty, Penny finally replied, "And you think you could?"

"Given my complete knowledge of everything, it would be reasonable that you would believe that I possess the requisite knowledge; and by this point, my lack of practical experience may be outweighed by your needs."

Leonard finally got Sheldon's earlier insinuation.

"I satisfied her! Didn't I Penny!?" he shouted, turning from Sheldon to Penny.

She ignored him.

Penny and Sheldon continued their stare down. She knew he'd said that she might think he was good enough, not that he thought he was good enough, but now wasn't the time for pesky little facts like that.

"You know what, Sheldon, I'm calling your bluff. Knowledge of everything my ass, I don't think you can."

"I only said you thought I could."

"And I'm saying you can't. I'm saying," jabbing her finger in his chest, a look of junior rodeo on her face, "you can't do any better than he could!"

Leonard may not have been following the conversation, but that he understood just fine. But his sputterings were drowned out by Sheldon's calm, but commanding voice; "All right. You're on."

"9 pm. My apartment. Be there. And we'll see if your knowledge of everything really is as extensive as you think it is."

With that, Penny and Sheldon simultaneously arose, and after a final glare, turned on their heels and strode off to their respective bedrooms.

As both of them shut their doors behind them, they both had exactly the same thought; "what on earth have I done?"

Penny rolled over onto her back.

Apparently Sheldon's working knowledge of everything really did include everything. And lack of (any) experience be darned, he was certainly better than Leonard. Heck, he was better than anyone. Eidetic memory apparently did have its advantages.

A/N: I can't believe I actually wrote this. I never had any intentions of writing a story with them actually having (implied) sex, and yet here this is. Oh well. Hope it was enjoyable. Now back to my other stories.