A person who acts like he/she can get anything he/she wants because it is his/her birthday.
Jonathan demanded that everyone should bring him a present to his birthday party, those that didn't bring anything were kicked from the party.

Jonathan: Dude wheres my present?

Kevin: Sorry was in a rush to get here and I didn't get time to get one.

Jonathan: Get the fuck out!

Kevin: Dude your being a bday dbag.
by A bday dbag October 6, 2009
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