The website got a bunch of former couples to sit down and take lie detector tests . . . and let THEM ask each other the questions.

Imagine sitting across from one of your exes and being able to ask he or she anything, while they are hooked-up to a LIE DETECTOR test!!! What would you REALLY want to ask your ex that if given the opportunity.

Of course, cheating comes up in this video, and chances are it may come up if you were their seat.

By the way, is kissing a forming of cheating? According to one guy in the video it is NOT.