1) Son in college goes out with the guys
2) Mom goes out with her girl friends from work they end up same club as son and his friends.
3) Sons friends don't know his mom and they end up picking them up with out son knowledge because he is trying to pick up another girl and it's a big club.
4) sons friends text him telling about the MILFs they are hitting on and are taking back to one of the guys home. Son said he will be there later if he fails with the girl he is hitting on.
5) Son fails and goes to the house where all the guys are at. The women are having sex with the other guys and he then notice it's his mom and her friends. He watches for a while then joins in or leaves.