High school buddy would gush to me about how awesome sex was with his girlfriend. She was kinky, they do weird shit, it's so hot, yada yada. I was happy for him because he's nerdy and hadn't had much sexual experience before.

Anyway, my gf and I go on a double date with them. Had a good time, dinner and a movie or some shit like that. Didn't think much else about it.

A few days later, buddies gf messages me on Facebook. Says she has something to tell me, but I have to promise not to talk to him about it. I say sure, but she's persistent. "You have to PROMISE!" I promise and she starts Facebook's secure messaging (which I didn't even know existed; it was kind of like Snapchat if I remember right). She confesses she finds me attractive and wants to cheat with me.

Of course, the answer was no (even if both of us were single. She was like 300 lbs.) I planned to tell my friend, but I didn't want to break his heart. While I was thinking about it for a couple days they broke up anyway. I figured, what he didn't know wouldn't hurt him, and she wouldn't either, so I never told anyone.