People doing that to you at parties or social events want to generate some cheap laughs and popularity at your expense. The best way to foil that, is to make sure you can top his insults, turn them around on him so to say. That would be poetic justice too. However, that's easy to say, but quite hard to do though: and if you fail to deliver a good retort, the results will in all likelihood be worse: your troll might take your failed attempt and use that against you as well.
If you can laugh it off, that's a decent solution. It shows him you won't be belittled or shamed by his humor, and it doesn't force you to try and one-up him at his own game.
You can also try to ignore him, but that might be hard: your mocker might see that as a challenge, and redouble his efforts to belittle you. However, if people see you refuse to be a target, they'll eventually get tired of trying and move on to other prey.