Looking for good bait

[jesustortilla]

Hey folks! I need help finding a good episode to hook my sister on the show. I've already got the recent episode where Penny dislocates her shoulder so I need one more. Preferably Sheldon/Penny focused and something that doesn't take a whole lot of back story and explaining to understand. Oh, and also preferably one where Penny is the funny one (intentionally or not) because I think my sister will identify with her the most.

Thanks for the help! <3