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2.
Abbreviation for Boobs In Your Face

Used online as a greeting, goodbye, or just in general conversation during instant messaging, text messaging, etc..

Generally a positive thing to say to a guy, or anyone who has an affinity for breasts.
"Ok see you tonight. biyf"
by Jim007 June 27, 2007
 
1.
meaning - "boobs in your face"; an expression used to wish good luck, congratulations, to wish good things upon a person, or a general positive greeting
Hey Jim, I hear you graduated! Biyf!
by w00tsean June 27, 2007
 
3.
meaning "Balls In Your Face"
Can be used as a greating, fairwell or state of tranquility.
Can also be used at any time found fitting.
Jenny: "Hey Tom, how ave you been?"

Tom: "BIYF!"
by assmasterupyabutt March 02, 2011