I guess there are two possibilities here.

Firstly, it's the alcohol and he's actually an OK bloke. If so, get someone who knows him to give him an earful when he sobers up. Getting told that you've trashed someone's day when you were drunk has a real chilling effect. Having screwed up someone's party at uni by getting drunk, I know. :-( Long-term it works. Short-term, get said friend or the police/stewards to move him.

Secondly, he's just an arsehole and the drink makes him worse. Not much of a way of solving that one.

Graham.