A group whore is someone who joins every single online group they see, whether they have anything in common or not or even if they don't agree with the message. Group whores usually only join an online group because they notice a large wave of people are joining and they want to be part of the "cool kids".
This applies to MySpace, Facebook etc.
Jenny has joined "I LUV THE TORONTO MAPLE LEAFS"
Jenny has joined "orlando bloom is a cutie"
Jenny has joined "the leafs fucking suck"
Jenny has joined "I am so random loL!OLOLOL"
Jenny has joined "Cat lovers"
Jenny has joined "Irish Republican Army"
Jenny has joined "I am bi-curious"
Jenny has joined "My Chemical Romance Fan Club"
Jenny has joined "I eat off the floor sometimes"
Jenny has joined "I am a total group whore"
A group whore is someone who, during group projects in school joins one group only to leave it for another and then comes back and then leaves again while still pretending to be part of the original group.
Callum: Hey, can I join your group?
Callum: I'll be right back (goes to other group)
Lucas (in Anthony's Group): What's going on.
Callum: Ok, what's the answer to number 5?
Anthony: I'm not telling you!
Lucas: You're a group whore Callum!
The girl in your friend group who feels the need to attempt to date every single one of the friends for no apparent reason.
Mike: "Wow, Sarah's dating Tim already? She literally just broke up with me 2 weeks ago.."
Chase: "Dude, don't even bother. That girl is such a group whore".