From my experiences of hanging out with different people while casually having drinks at a bar or clubbing at night clubs, I have observed three breeds or... types of drinkers.
Type 1's are those that become very boring and quiet when they start drinking.
Type 2's are the ones that get out of their comfort zone and basically are entertaining.
Type 3's are the out-of-control individuals. They can't be tamed! Stay away and be nice at all costs!