A generic greeting used for those (un)fortunate enough to have their birthday on December 25. Usually followed by: "I would've gotten you two presents, but..."
Person 1: Hey man, Mappy Birthmas!

Person 2: Aw thanks dude! Now, what did you get me? *evil stare*

Person 1: Well, I would've gotten you two presents, but...

Person 2: Ugh! This happens every year!
by Aussie Rhys December 25, 2009
Get the Mappy Birthmas mug.