What are some good games to play at a big party for 20/30somethings?

I'm having a big party, probably 50 people will be attending, there will be lots of booze, music, food, board games, video games set up, TVs, etc. BUT, I want to have some really awesome games set up to be a big event at the party, with prizes, etc. I can't think of anything. What are some good big fun games that adults (that normally wouldnt play games) could play? Most of us are into rock music, punk, and are fairly rowdy. Thanx!