One time I mistakenly went on a double date with a friend of mine, his girlfriend and her best friend.

It went horribly wrong. I ended up feeling like a fourth wheel and I accidentally offended the girl who I was supposed to be "dating". I was unaware of this until a few weeks afterward so that lead to a whole series of complications.

We went to see a movie, I sat down and she acted as if she didn't want to sit next to me. That offended me, leading me to sit by myself which had offended her more than she had already been offended.

All in all, it was a horrible night and I ended up crying during the first hour of the movie, she stormed into the restroom and had an emotional breakdown and I ruined a friendship with someone that I've known since the 7th grade.