I work in finance and our Christmas party is always sleazy.
Some people get so drunk before they arrive that they spend the evening being sick all over the toilets. Or stagger about falling over and trying to talk to people, but they are so drunk they can't get any words out.
Some of the female managers are notorious for turning up wearing very revealing outfits. They usually end up grinding on the dance floor and kissing each other. Also a couple of years ago, they grabbed one of the senior execs (older gentleman, very quiet and reserved) and they clawed his shirt off
ripped the buttons off and everything. He looked like he wanted the ground to swallow him up.
Then of course there's always the married people getting it on with other married people. Hate to think of their partners at home with no idea of what their spouse is really like. Next day is always awkward in the office.
Finally, we have the creepy gropers. Being a relatively young female (30 now but have worked there for 10 years) I've lost count of times that older, usually married men have tried it on with me. This year a guy I've never met (I'm on mat leave currently) decided to leer at me that he's 'got a thing about women with dark hair' and proceeded to follow me around staring at me all night. Not at all intimidating!
Of course, I always leave early 
Luckily these people are in the minority and the colleagues in my team and really nice. Otherwise I suppose I wouldn't go!