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 3, 2006
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Half a boner for no apparent reason.
I was at my son's bris ceremony when I got a HABFNAR (ha-boof-nar) and was asked to leave by the rabbi.
by Richard Lewis III January 26, 2009
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