1. Have four guys fuck a girl.

2. To run four World of Warcraft accounts on one computer on the same screen.
Me and four friends Quadboxed the shit out of that bitch last night.
by Shanus Teh Anus June 18, 2008
simultaneously consuming four tabs of pornography on the same screen, while aggressively masturbating.
Bro I just fucking quadbox'ed so hard its gonna take my balls a week to refill.
by poshzilla March 21, 2020