1 definition by Dr. Moo

The mutual boyfriend that only appears when another male becomes interested in the female
Bob: So ya wanna go out this friday?
Sarah: Sure! That soun-......
Jim: Hey hot stuff!
Sarah: Hey! Bob this is my boyfriend Jim.
Bob: Ummmm, WTF?

Jim is a Closet Boyfriend
by Dr. Moo May 16, 2007
Get the closet boyfriend mug.