Posted by Sabrina B. @gametimegirl

UFC face pummeler Rampage Jackson got one crazy request from a balsy fan last night — dude wanted to get SLAPPED IN THE FACE … and Rampage obliged.

Rampage was leaving Greystone Manor nightclub in L.A. … when a fan with a pain fetish approached Jackson and asked to be cracked in the mouth.

Never one to deny a fan …  Jackson bestowed the 5-finger honor across the fan’s jaw — and the fan couldn’t have been HAPPIER!

TMZ