Sheldon: Leonard, you have to do something about Penny. She is interfering with my sleep, she's interfering with my work, and if I had another significant aspect of my life, I'm sure she'd be interfering with that too.
Leonard: Why should I do something? You're the one who introduced her to online gaming.
Sheldon: Well, yes, but you're the one who said hello to her when she moved in. If you'd simply restrained yourself none of this would be happening.