This is more of a threat than an insult, but it's certainly memorable:
"I'll say it right to his face in cursive because he knows if he comes over, I'll scissor kick his gizzard and break his karate artery."
-Donnie Baker
https://youtu.be/FhQDsKoMCz0?t=1m3s
Its worth watching the whole 2 minutes, where you'll hear insults like:
"we ain't supposed to have livestock in this neighborhood and yet you married a sea cow."
and
"She was eating Bugles like Nabisco needed their bags back"
Edited by Cat Sci, : typos