For me it was the one where Jerry accidentally squirts grapefruit juice in George's eye, and he keeps winking at people uncontrollably. That episode always stuck out for me.
WOW!!! They're all pretty good but one of the shows my friends always joke about is the "Soup Natzi" stuff. hahahaha....damm that show was good. I wonder how good it would would have been if they wrote a script for Charlie Sheen into the show? That would make a funny reunion show.