It's a familiar sight in Boston: Some hapless college student is fumbling to find her driver's license for the doorman, only to be asked for a second form of ID. And if she can't find it and looks particularly young? Buh-bye. Boston's bouncers are a fearless lot, and out-of-towners should be ready to prove they're 21-plus. Plan to be in good company by 11 pm, but the party's over at closing time: That's 1 am in many neighborhood watering holes, and 2 am sharp in nightclubs and hotel bars. Also keep in mind that the T conveniently stops running at 12:40 am.