When a female reaches between a man's legs from behind to grasp his cock and balls.
As I was leaving the party I was surprised to receive an undercup while in mid-step. Unfortunately, when I turned around she was built like an offensive lineman so I ran away feeling violated.
by dat.bro February 21, 2011
Where by a group of Lads grab a young skets breasts from under the top and often leading to a bukaki.
" Hes only gone for undercup and she loves it."
by Slaps December 07, 2009