Used as a joke to rip on friends when you see an ugly girl or old lady. substituting a family member for girlfrined is also very effective:
by TommyGun July 14, 2005

An Internet-Girlfriend; the couple have never met each other in real life, and the entire relationship is based on email and/or instant messanger conversations.
by RachBU January 24, 2008

A girl who a guy only sees on the weekends because he is not really serious about her. Typically, he is only with her because she is offering something to him on said weekends (ie, sex).
Q: I didn't know Carrie was John's girlfriend. A: Oh, she's only his weekend girlfriend, nothing serious, just sex mostly.
by Arealgirl August 31, 2012

Looking after you're mate's girlfriend while he's away (for a short or long period), and treating her as if she was your own.
Person 1: "Who's that girl that James is with? Is that his mrs?"
Person 2: "Nah, he's just girlfriend sitting for a few weeks"
Person 2: "Nah, he's just girlfriend sitting for a few weeks"
by Pillobeam September 14, 2009

An Australian magazine for teenage girls, teaches them to believe in themselves, like their self image, love themselves and not to go anorexic like half the super models in other magazines. Also teaches methods of masturbation.
Girl:"Have you read this months 'sealed section' of Girlfriend magazine, shoving barbie dolls is the new thing, it works too".
by coopz March 12, 2008

tyler edelman: "phone with sarah!"
nahja: "who she?"
tyler edelman: "this sexy babe i met on myspace now she's my myspace girlfriends."
nahja: "ahhh shittt, he's at it again!"
nahja: "who she?"
tyler edelman: "this sexy babe i met on myspace now she's my myspace girlfriends."
nahja: "ahhh shittt, he's at it again!"
by Jay-Loose December 13, 2009

A mistress. A sexual partner that is unknown to the rest of the world, she is kept hidden from the public, and from the publicly proclaimed girlfriend and wife, mate, live-in spouse.
by GEO Z October 14, 2006
