Sheldon: Are you bothered that I can so easily manipulate you?
Howard: Don't push me, Sheldon. I may be small, but I took kung fu when I was 13, and I remember a good deal of it.
Sheldon: Oh, really? Well, I grew up with an older brother and a very contentious twin sister and I believe I could easily best you in any physical confrontation, be it noogies, swirlies or the classic why are you hitting yourself?