Informal position for sexual intercourse which requires the participation of two males and two females. It's widely known as the Sandwich of Sex. The first male and female begin in missionary position, the second male then lays on the back of the first male, then finally, the second female mounts the upward facing male... thus the booty melt.
Origin: RIT 2011 (DC&Kel)
dude#2: Yeah man, I seen't it already
dude#1: I wonder if they're down to do "the Booty Melt" tonight?