Definitions by Phil My Pockets

friend who happens to be a girl 

a girl you have sexual relations with on occasion. She's not your girlfriend, not exclusive. When introducing her to your buddies you say shes a friend who happens to be a girl. Your buddies know you can still hang out just the same as at it always was.

Meet Jennifer, shes's my friend who happens to be a girl (not my girlfriend).

friend who happens to be a girl by Phil My Pockets July 29, 2016

BYOGF 

Bring Your Own Girl Friend

The party tonight requires not only BYOB but also BYOGF

BYOGF by Phil My Pockets May 18, 2014