Fartknocker
An infamous childhood insult. A bridge between more daring and colorful grown-up insults such as motherfucker and shithead.
Anna: Uh, Jake, clean up your room for once.
Jake: Maybe I will if you leave, fartknocker!

Immature Adult in bathroom washing hands: Huhuhuhu, HEY FARTKNOCKER, I CAN SMELL YOUR SHIT! *Runs out of bathroom*

Adult in the bathroom taking a dump: Motherfucker.. shithead.