WhipBack, also known as "WhackBack", is a pain-inducing game played by teens and young adults who use leather belts to create self-inflicted welts on their backs.
I laughed my ass off all night because Billy wouldn't stop playing WhipBack.
Originating from the idea of ordering the most obnoxious drink at the bar, whipwacker can be likened to an obnoxious person or group - specifically used for bachelorette parties in Nashville.