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2.
Duh; a twelve pack. usually of beer but can be soda.
Duude! He downed my whole twelver!
by jimmyvix May 14, 2010
 
1.
An individual who believes in and spreads the various myths and hoaxes associated with the termination of the Mayan long-count calendar on and around December 21, 2012
John Doe: Hey sis, did you hear that Woody Harrelson's a 'twelver'?

Jane Doe: A what?

John Doe: A 'twelver'. You know, someone who believes the world is going to end on December 21, 2012.
by Hawkins' bitch July 31, 2011