The
age that an American citizen, having been able to enlist in the military, purchase tobacco, vote, and enter a strip club for
three years
already, can finally go and buy a can of beer.
Guy 1: "Hey, I heard you're 21
today! Here's a beer!"
Guy 2: *puffs
cigarette, shouting over strip club
music* "Thanks, dude. Now I'll finally know what being an adult feels like."