Everybody gets one.

The party apparently started at 11:30 PM. At least that's when I could clearly hear loud talking, thumping bass, and whatever rap song was popular this weekend.
I've never had a problem with my upstairs neighbors before, so I figured I would give it some time, and be a tolerant neighbor. After about an hour and a half of reading (and an apparent time change), the music had gotten louder. So I got dressed, climbed the stairs and rang on the doorbell (it should be noted that I couldn't hear the music outside, but very clearly in my apartment). No answer after ringing it twice. After banging loudly and angrily on the door, an apologetic young man opened the door and asked if the music was too loud. No, I'm selling girl scout cookies at 1 in the morning. The music was turned down.
I went back to sleep. At 3 in the morning (after the time change, so... 4 really), I woke up to loud bangs coming from upstairs and my light fixtures shaking. The music was louder than before, and I could hear yelled conversations clearly. On top of that, they must have been having a body slamming match, because every thirty seconds it sounded like my ceiling was going to cave in.
Being the nice guy I am, I called the security company for the complex instead of the police. That's when the music halted completely, and things got really quiet, really fast. I am not happy, however, that the security guard did not stop by my apartment to make a report (as the the police would have done). I could not get back to sleep until the sun came up.

Everybody gets one. Next time I'm calling the cops without even giving a warning. Seriously, loud music and talking is one thing. But loud bangs every thirty seconds at four in the morning on a second floor apartment... that's just dumb.