A slang term, used in place of the more "correct" term for ejaculation. The term originated from when sperm would bust from the testicles (nuts). Not to be confused with "bust your nuts" meaning to smash the testicles.
When one, usually with little impulse control, cannot help himself hold back cumming. When a guy jerks off and then ejaculates, usually in a short period of time, having been highly aroused.
1. to ejaculate 2. to exert one's self greatly (comes from how one might get an inguinal(groin) hernia from over exertion)
John: Yo, Jim's sure busting a nut with the yardwork, eh?
Don: Yeah, his wife promised him as threesome with her lezbo cousin if he gets it done today!
John: Then he'll REALLY bust a nut, eh?
Don: Ideally, yes!