Ask A Ninja: Question 19 "Physics"
"Ok, yes, Physics and I do have a relationship. It's not exclusive anymore. I mean, we were for a while, but to be honest with you, she was really holding me back."
Two other really funny ones (actually funnier than the physics one, but I'm partial to the physics one for obvious reasons) are:
Ask A Ninja 18: "Minjas"
Dogtoons.com Asks a Ninja Scroll down to the second video box.
You’ll hear the opening song and want to turn away. Don’t. It gets better. Much better. :)