backside

/ˈbækˌsaɪd/

noun

A person’s buttocks or rump.

buttocks,behind,backside,bottom,rear,rear end,seat,haunches,cheeks

adjective

(of a maneuver in surfing and other board sports) done clockwise for a regular rider and counterclockwise for a goofy rider.

Next would be big backside floaters or under the lip lay back snaps.