Don't think anyone is going to top Alan's story.
Mine are pretty innocuous in comparison. Made arrangements to meet a girl at a club (she didn't want me to come pick her up). Ok a little unusual, but not terribly. When I got there, she had brought her best friend along. I got to buy drinks for both of them, while they chatted. She didn't want to dance, even though we were at a club with good dance music. After being ignored for most of an hour, I left.
Went on a double date with my then girlfriend and my best friend and his date. My friend's date decided she liked me better and hit on me all night. It was a miserable evening, especially since my girlfriend decided it was all my fault. (by the way, when is it ever not the guy's fault?)
High school girlfriend decided she wanted to get really drunk. As I was driving, I had virtually nothing to drink. While it was a little amusing to watch her slide into a completely blitzed state, it was much less fun at the end of the date. She couldn't walk without assistance and when I tried to pick her up and carry her, she slipped out of my arms and conked her head on the curb. Got her into the house, where her dad was watching tv and her mother was asleep. Her best friend was sleeping over, so the friend and I tried to get her into her bedroom...at which point she started vomiting all over the place. We managed to get her to the restroom, where she seemed to upchuck for 20 minutes straight. Lots of cleanup. I could hear her dad laughing his butt off in the tv room.