n. A word used to insult somebody, means basically the same as kunckle head. Knuckle-head is to knuckles in your head, as chuckle-butt is to chuckles in your butt. Can also mean one who farts a lot.
Daughter who is texting her friend on her cell: Daddy, my friend just said i was stupid!
Father: Well, call her a chuckle-butt
Girl-Ew, Chris is such a chuckle-butt
Other girl-Tell me about it. Earlier in math class he blew one right in my face!