Later, the same people will physically display all signs of being drunk, but will claim to be sharp as a tack, because, as they'll tell you, they drink so much that it, like, would totally take all the booze in this place to get them drunk. Then they'll plow their Mustang into a drainage ditch and take a swing at a cop.
Don't step on his shoes, don't make incidental eye contact and don't talk to his girlfriend. If he doesn't have a girlfriend, don't talk to any girls because they could be his girlfriend, someday. It doesn't take a whole lot to set this type of guy off, and after he's pissed, screaming and swinging you'll wish you'd actually done something worthy of such a tantrum.
He's easy to pick out in a crowd, there'll be one man yelling while everyone else in the crowd exchanges confused glances along with sympathetic shrugging shoulders. He's the screaming one, the one trying to finish an imaginary fight with a person who didn't start it. A douche that can't be ignored.
This is a classic case of Intermittent Explosive Disorder or IED. This guy is a time bomb, and nobody can see the timer but him--he can go off at any moment. Although his aggression normally isn't life threatening, it's really fucking irritating. Medically diagnosed IED is defined as a behavioral disorder characterized by repeated episodes of aggressive and violent outbursts grossly out of proportion to the situation. Wearing a sleeveless rayon body vest while stinking like Axe body spray is common but unfortunately correlation does not equal causation.