Or any similar show- I couldn’t find a previous thread on this. Anyhoo, mine would be that Burns thinks he’s never met Homer- “Excuse me, sir, we’ve never met” 
Or at least until a few years ago. That’s sort of why I detest the Simpsons orienteering episode where Burns and Homer become pals- ugh.
“Midge.”
I think for me it would have be Homer’s bizarre lifelong dreams, and the even more bizarre lifelong dreams Marge always reminds him he’s fulfilled. “We got more gongs than that breakdancing robot that caught on fire.”
Rakes!
One I miss from the early seasons is when Quimby and Wiggum go into intense film noir speak about who actually runs the town. Such a power struggle.
Most overused catchphrase, ever.
I love that Marge’s maiden name was Bouvier.
“Yoink!” still makes me laugh for some reason.
I love all the Quimbys as Kennedys parodys.
Ralphie Wiggum.
The lowly life of Hans Moleman. “Nobody’s gay for Moleman.” Heh.
Hard for me to pick a favorite though. Maggie has a few. The pacifier and the fact that she falls on her face every two feet are good. Also, Homer tends to forget her as one of his children:
I do enjoy surprise appearances by Crazy Cat Lady.
That pretty much anything that crashes or falls will blow up.
I love duffman appearances
Duffman cannot die, only the actors who play him.
My favourite running gag ever was Trigger calling Rodney “Dave” in Only Fools and Horses . Pretty much perfect timing whenever it was done.
Not a running gag per se, but I like that Milhouse Van Houten has Nixon’s middle name for a first name, and the name of one of the Manson killers for a last name.
Also Mussolini as a middle name.
My vote is 'ol Gil. Guy can’t catch a break!
Disco Stu, who was supposed to be a one-shot character.
And according to Wikipedia, his middle man is Mussolini- was this ever mentioned in an episode?