Tall boy: n. A 16-24 oz. can of beer. (Slang)The Free Dictionary and Answers.com say 16 oz. but Urban Dictionary argues:
If we can all agree that the can must hold a lot of beer, I think the understanding will be sufficient.
Also know a as a tall can. A 24 oz can of beer. Not to be confused with a pounder a 16oz can of beer, or a deuce deuce a 22oz bottle of beer
Forever immortalized by Har Mar Superstar:
(Fun fact, Har Mar told Daytrotter that he wrote this song for Britney Spears!)
Tall boy, The Free Dictionary
Tall boy, Urban Dictionary
Tall boy, Answers.com