Casually bring it up as a side note as if it were a joke. Then if he does it again, add to the joke again with very casual reference, to make him seem somewhat stupid/uncool/uncoordinated. I'd suggest throwing it in shortly after starting a sentence about a completely unrelated matter. On the psychological level, if it's witty and damaging enough, he'll feel self-concious or ashamed about it. If you throw a handful well placed witty lines to make him look suitably inferior, I'm sure it would get to him far more effective than a complaint.
For example (Poor one, but I'm not feeling witty today), "Hey, You know that paper I was... *very short pause for slight emphasis* you got a little err... *rub side of mouth as if indicating bit of food* 5 course meal coming out you're mouth there *Very short laugh and continue*. Yeah, the paper I was talking about the other day, [etc]"
Saying that, it doesn't work on some people, and you might not be able to deliver it effectively. It's all about the psychology of it though. Find out what he's most defensive reaction is to forms of psychological attack. Key is to keep it short and casual so he gets the point without thinking you've got a big deal with it, weather you use anger, disgust, comedy, or other way to express it.
Then again, I did end up having 3 fights with my roommate at uni (Mostly because he was an aggressive cocaine addicted alcoholic that always felt the need to be the "big man") and I'm thinking too much from theory than practical experience.
So failing all others, tell him to step outside.