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1.
A secret code word among males used to explain the cause of a spontaneous erection. Habfnar means to Have A Boner For No Apparent Reason, such as when waking up in the morning, or just at any time in general.

Pronounced: Ha-boof-nar
"Dude, I habfnar"

or

1: "Someones excited"
2: "Habfnar"
by Michael MySpace September 02, 2006
 
2.
Have A Boner For No Apparent Reason
Is used to signal to anyone else who knows the term that you have wood for no reason. "Hey, H.A.B.F.N.A.R., right now!" (while in a room full of unknowing people)
by Michael Roarty March 28, 2007