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1.
Slide your fist into someone's asshole and spread all your fingers out all at once.

Much like the regular hand grenade, but instead of using a vagina, you are using an ass hole.
"Did you hand grenade that chick last night?"
"No, but I did do a reverse hand grenade!"
by muffinhasmypants April 19, 2009

Words related to Reverse Hand Grenade

asshole butt fingers fist grenade hand hand grenade reverse surprise