When you realize that you don't REALLY know all of those people on Facebook or if you have to "Hide" all of their posts or invitations. It is then that you have to do a "Friend Dump" also known as defriending.
friend dump defriending friends facebook
Person #1: Dude. You have 357 friends on Facebook?
Person #2: Hey man, I USED to have 533, but I did a big friend dump and now I'm down to 357!
To dump a friend or stop being friends with someone.
Normally occurs as a result of someone being particularly lame.
"john why are you talking like that?"
-"cos i real hombre"
"someday i'm gonna have to friend dump you."