Season 2 The Friendly Physician
Skipper:"Run your hand across the top. There must be some sort of lock or something!"(Gilligan takes the Skipper's Skipper hat off and runs his hand on Skipper's head.)
Skipper:"Not my top, you dumb bell!"
Gilligan:"I'm not so dumb."
Skipper:"Oh yes you are!"
Gilligan:"If I'm so dumb, then how come you're in there, and I'm out here!?"