1. Sex that is had with an ex months or years after the break-up with both parties acknowledging that it is simply sex and there is not a chance in hell that the couple will be getting back together.

Reunion sex is really good sex in that you wouldn't go there again if the sex wasn't good when you were in the relationship with the ex. It's comfortable, no strings attached sex that should only happen once every 6 months after break-up.

2. Sex with a previous sexual encounter whom you believed or intended to be a one-night stand thus making it a two-night stand or more... aka Reunion Sex.

the thing that you don’t have when you’re phones percentage is over 20