1 definition by The Red Bull

pronounced (biff-t-nag.)
an acronym standing for either Best Friend That's Not A Guy, or Best Friend That's Not a Girl. Used in cases in which very good friends are of the opposite sex. a person has the same relationship with a bftnag as they would a best friend.
Phillip and Katie are bftnags. They tell each other everything, and have complete trust in one another.
by The Red Bull May 27, 2008
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