They've become that on their own. We didn't think of it as a catch phrase, yet it turned up on many weird places. I think there's even a T-shirt. We try to make Bart inhumanly clever, so many of his phrases like 'Don't have a cow, man,' already exist. We were just trying to portray what kids would really say.
Some references are actually a bit closer to home.
Every time any little detail works its way in, like the couch being held up by a dictionary, it's either a very happy or somewhat annoyed reaction. I have occasional references, like a cousin who spends way too much money on lottery tickets. I use different people for different things. My brother tends to be Bart, my cousin tends to be Homer. Simpsons creator Matt Groening wasn't at all the sort of person the story editor thought he would meet, Vitti admits.