Dum Bass

Alright, listen up, numbskull. This joke is playin' on words. "Dumb" means stupid, and a "bass" is a type of fish. Put 'em together, and you get "dum bass," which sounds like "dumbass." See? It's funny 'cause it's makin' fun of stupid people. And since you need me to explain it, you're probably one of 'em.