Green’s Dictionary of Slang

ass-buster n.

[ass n. (2) + buster n.6 ]

1. (US) a dive in which a swimmer jumps, holds their nose and hits the water buttocks-first, the aim, and the result, being to make a big splash.

[US]Harder Collection n.p.: Ass-buster: A dive in which the diver holds his nose, jumps, and hits the water arse-first [DARE].

2. an outstanding person.

[US]S. Ace Stand On It (1979) 101: Cousin Ned was right. Yer going to grow up to be a real ass-buster.

3. a fall.

John’s Page [Internet] After stalling the grind correctly, try a good rail or a nice curb. Too much wax on the first grind will also cause an ass-buster.

4. something challenging.

ebtx.com [Internet] I took that test and did every question (right or wrong) by myself. So I can say with authority that it was an ass buster.