Haircut records.

Penny and Leonard are playing Chess while Sheldon works, or at least tries to. He keeps sighing and looking in a mirror, then taking a micrometer to his hair.

Penny looks over the chess board with a grin and moves a piece "So, if I move my horsey here... Isn't that checkmate and I win?"

Leonard frowns. He's been looking more and more worried as the game progressed and now he steeples his fingers in front of his face and lets out a long "Hmmmm..."

Penny grins and points at the board "Well, is it or isn't it? look, your king is trapped. He can't go here because of my lighthouse, and he can't go here because of my pointy-head guy.

Leonard looks over at Sheldon accusingly:" Sheldon, did you teach Penny how to play chess? "

Sheldon looks up from his computer "Did I teach her? No need. She's a remarkably fast learner. Come now Leonard, you must have noticed by now that Penny isn't unintelligent, merely rather uneducated. Give her a straightforward set of parameters like chess where complexity is derived and she'll give you a run for your money, and I should remind you that you were hothoused by a genius."

He sighs.

"it looks like Mr. D'Onofrio won't be returning to his business, he's leaving it to his nephew. So now I've lost all my recent haircut records. I wonder if my mother still has the original set ? they'll be criminally out of date but I'll have to start somewhere." he reaches for his phone.

Penny gets up "Ok, I sense your mothers understanding touch in this. Tell me about your 'Haircut records' honey"

"As the name implies, they're records of all my haircuts. How else would you have your hair cut?"

"Of course, less change means less worries. Homeostasis, right? ok, how about we look back over all our pictures and put together a collection of the ones with your hair looking correct in them?"

"we'll make our own copy of your haircut records, once we have it just right we can make a portfolio with some 8 by 10 glossies. Then you can make sure any hairdresser you judge trustworthy and skilled enough has the right records. How's that sound?

Leonard pipes up from staring at the chess board "You could even combine them and render a 3D model of your head!"

Penny turns round and hisses at him "Don't make it worse! If I were you, I'd be more worried that a girl who's never played chess in her life just kicked your ass!"