look up any word, like the eiffel tower:
(v.) The act of hooking up with your ex's current partner's ex after discovering that your ex is hooking up with the target's ex.
Ex: Jenny and Alan used to date. Chrissy and Dave are dating, but Chrissy leaves Dave for Alan. When Dave and Jenny hook up, they are "completing the square".
by thedl February 28, 2008