Mine was in 7th grade. My girlfriend at the time was a big party goer and I wanted to show her how cool I was, so I went with her. I had had beer before, but it was only a few sips from my Dad's beer every now and then.
We got to the party at our friends house and it wasn't really my crowd, but we went to a very small school (around 100 students in my class) so I knew everyone at least. They were all surprised I showed up and most of them were already very drunk, they were passing around a handle of liquor and drinking beer as well.
We weren't there for an hour and everyone, except for me and one other girl I was friends with, was completely hammered drunk, one kid almost fell into the bonfire. Then things got a little sketchy and one of the kids pulled out some drugs, I later found out they were hydros, and started passing them out to everyone. I passed on that as I was started to feel drunk and we had just talked about synergy in health class, so I was worried I might die or something.
At this point everyone is either melting into the chairs around the fire or running into the woods yelling, and then the girl's father whose house we were at came outside to see what was going on. I immediately thought we were fucked, but once they noticed him coming out, they all calmed down and kept their composure until he left.
Either her Dad didn't care or they had done this sort of shit so often they hid there drunkenness well. Shortly after that some one jokingly told my girlfriend I was cheating on her and she started yelling and crying in my direction. She was so drunk she thought it was true and I had to calm her down. She wasn't listening and shouted, "well now we're even" or something to that extent. Everyone got quiet and someone told her that it was a joke and the she looked at me and tried to say she was joking as well, but I knew she wasn't.
Shortly after that my girlfriend's Mom picked us up and I had one of the most awkward car rides of my life and then broke up with my girlfriend over AIM that night, because that's the way it went back then.