In a group setting I've found the best way to deal with someone else trying to assert dominance over you is to treat them like a little kid and make it clear you're not taking what they say seriously.

But what about when the guy is throwing low-blows at something like your height, a chipped tooth, a big nose, or some other physical quality, but you can't fire back anything on him because he's a 6 foot 4, tanned, muscular guy with perfectly symmetrical features and a mouth full of Dentist's-Monthly worthy teeth?

Also, what about when he starts getting really personal, saying things like "no one here actually likes you", "You're actually really stupid. I'm not kidding right now. You're an idiot."

When it gets to that extent, I feel like standing there and ignoring it makes you look like a bitch to everyone else who's watching, but at the same time, walking away would look even worse.