There are too many iconic 30 Rock jokes to name. But I'll start with my favorite. "You're magic jeans are from BDL? Oh Lemon, it's not hand-made in USA, it's pronounced Hand-made in Usa. The Hand people are a Vietnamese slave tribe and Usa is their island prison." I'm sure when I'm 99 and mostly senile, that moment is still going to be knocking around in my brain. True story, I once ran into the actor who plays Jonathan (Jack's assistant) while I was out dancing, and he said he liked my outfit. I was soaring for days.
30 Rock is one of those shows where the joke density is so high that it almost demands a rewatch. They fire so many jokes per minute that the writers should be given a slot in the Olympics. I'm not sure for what sport, all I know is that they're beating Young Sheldon.