For some reason, the funniest moment in Seinfeld for me was in The Marine Biologist→[More:]

Not the speech at the end which is apparently a classic moment of the series, but near the middle when George reacts to Jerry having told a woman that George is a marine biologist. I couldn't find it on youtube so I uploaded it: https://www.youtube.com/watch?v=tj0SLy9uUik.