Sheldon has experienced a lot of things he never would have planned on since Penny moved in across the hall. He has sung show tunes in a public place, thrown a birthday party, hugged someone who he wasn't related to, drank coffee, driven a car and been bested at Halo by a newbie.

But what he experiences on this particular morning is absolutely baffling. He heads to the bathroom at his normal time but freezes in the doorway when he sees her. Penny is squeezing out a line of toothpaste on her index finger.

"Penny?"

She puts the tube back on the sink and looks over her shoulder at him. "Sorry Sheldon, I promise I'll be out of your way in two minutes."

Sheldon clenches his jaw and lets out a loud breath. "That's not what concerns me. What exactly are you doing?"

Penny sighs and turns all the way around this time, leaning against the sink. He tries to gauge her facial expression and comes up with 'annoyed'.

"I'm trying to brush my teeth, oooookay?"

She rolls her eyes and grimaces.

Nailed it. That's definitely 'annoyed'.

"Brushing implies use of an actual brush. You have toothpaste on your finger."

"Okay. Then I'm trying to RUB my teeth. Happy?"

"Hardly. While a toothbrush is generally preferable, you can clean your teeth without one but you should wash your hands thoroughly first. Did you wash your hands?"

Penny puts her hands in front of her and looks down.

"Shit."

Sheldon takes a step in to the bathroom like he's about to lecture her. "Second question... Why, when your own toothbrush is no more than 30 feet away, would you choose this method?"

"I don't know, Sheldon. I was being lazy. What's the big deal?"

He nods toward the sink and puts his hands in the pocket of his robe. "You're using my toothpaste. Mine is the extra-whitening brand. Leonard's is the one in the Spider-man bottle. If you're going to be here sleeping in his bed, you should use his."

Penny smiles apologetically. "Okay, I'm sorry. Let me wash my hands and I will use Leonard's toothpaste from now on."

"Good."

Sheldon turns quickly and walks out of the bathroom to return to his room. His phone is lying on top of his dresser and that's when another one of his brilliant ideas hits. When he returns she's rubbing her teeth with her index finger so Sheldon aims and shoots, getting a perfect shot of her reflection in the mirror with his phone's camera.

Penny freezes at the fake shutter sound and turns slowly. Sheldon is grinning a bit too proudly as he slips the phone into the pocket of his robe.

"Sheldon... you didn't."

He just grins more.

"Why would you do that?"

"I have my reasons."

That's when her face changes. It's an expression he's seen before and nothing good ever happens when she's wearing it. Sheldon speeds out of the bathroom and into the living room like he's being chased by a lioness, and in a way, he is.

He makes it as far as the chair when she catches up to him. She tries to reach into his pocket but Sheldon turns in a circle like a dog chasing its tail as she follows him.

"SHELDON! HAND IT OVER!"

"Oh no, you'll have to get it yourself."

He takes this opportunity to fish the phone out of his pocket and hold it high above his head. Penny stops circling and growls at him. She tries to jump and reach for it but it's just out of her reach.

"OH MY GOD. NOT FAIR!"

"Sometimes life isn't fair, Penny."

Penny is literally seething as she stares him down, trying to strategize her next move. They both turn their heads when they hear Leonard walk into the room.

"Uhhh... what is going on?"

"Sheldon took a picture of me and he won't give me his phone so I can delete it! MAKE HIM GIVE IT TO ME."

Leonard looks to Sheldon for his side of the story.

"She was in the bathroom at the precise time that she KNOWS I'm scheduled to be in there. And she used my toothpaste! Tell her to leave me alone. She's YOUR girlfriend!"

Leonard's eyes look back and forth between them and he just shakes his head, turns around and heads back to the bedroom.

Sheldon still thinks he has the upper hand until Penny climbs on to the chair behind him and throws her arms over his shoulders. She sticks her index finger as close to his face as she can get it without touching him.

"Delete that picture or I will stick my disgusting saliva and toothpaste covered finger in your ear."

"You wouldn't."

She wags it right in front of his eyes. "Do not test me. I've done worse."

Sheldon sighs and puts the phone in front of him to show her that he's deleting it. When it's done, she removes herself from his shoulders and jumps off the chair.

"Thank you."

He gives her a begrudging nod in return and watches her as she heads back to the bathroom. Sheldon is pretty sure she's out of earshot when he snickers out loud. Penny doesn't know he had already hit send to have the picture sent to his e-mail account before she caught up with him.

Sheldon sits at his laptop and loads the picture into a password protected folder called 'just in case'. There it sits along with a few rather embarrassing pictures of Raj, Howard and Leonard. Howard eating pork (on the Sabbath, no less), Leonard dressed as Jar Jar Binks for Halloween (after losing a bet) and Raj canoodling with Richard the Slave Girl at Comic-Con (only Leonard missed that moment).

For what it's worth, he thinks Penny could have gotten off a lot worse than what she did. But he's certainly not above using what he has if the time ever comes that he needs to.