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1.
What you would call a bisexual boyfriend.
My bi-friend took me out to dinner and would not stop staring at the waiter's muscles.
by "US" January 10, 2010
 
2.
Ones significant other, whom is Bisexual. This Person usually participates in threesomes with other couples.
"So are you going out with Adam?"
"Nah, I'm going out with Dave, Adams just our Bifriend."
by ericmboll February 09, 2009