I have not seen more than half of the episodes, but this is by far the funniest I've encountered. These rank in my top twenty Seinfeld moments ever:
"I am not an animal!"
"You want a card? Here!!"
and story of Mr. and Mrs. Louis Pasteur as told by George is my vote for the Funniest Scene from a Seinfeld Episode.
-KM "Your buttocks are sublime..."