rump bump means that when a man grabs a woman/man by his/her hips and shoves his hard erect penis into her ass crack, while in the process of pulling his/her pants down. then, they shove the person on the ground, get on top of the person and rides them like a pony, then you go 69 on their ass

damn bitch, i had sonia over last night and i tried to rump bump her ass but it was too flat and nasty, and she was terrible.

damn hoe, i had m&b in bed last night, they were the best rump bumpers i know.
by Marissa(: June 13, 2008
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The act of sniffing cocaine, or other powder drug off an ass. "Usually a female stripper or prostitute"
She'lol let you take a rumpbump if you give her one too.
by Comeagain,saidvirginmary April 15, 2018
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