To "cleanse" one's facebook friends list of people that no longer belong there... that's right. To sweep up the creepers.
Person A: "Why did your friend count go from 1,324 to only 832? Anything you care to tell me about?"
Person B" "Oh that, well i just did a creeper sweep and eliminated all those people i don't talk to anymore. All they do is stalk me."
Person A: "Oh i see. Damn i should do a creeper sweep too!"