When a very hairy-chested man has gone the entire night without scoring a girl, in a last ditch attempt to get anyone's attention before the bar closes, he unbuttons the top few buttons of his shirt and shows of his sasquatch-like qualities.
This is the pick-up version of a rally cap in baseball.
Ronald: Dude, there are so many chicks here tonight but they all look taken.
Mikey: Break out your Rally-Squatch, it ALWAYS works.
Ronald: Cant tonight, I only have 5 condoms left.