Used as an alternate for defriending people off of Facebook.
action verb: The act of defriending a large group of people from one's Facebook because of a number of reasons (i.e. removing an ex, people you don't talk to any more, that random from the party last night, etc).
verb: to downsize one's Facebook friends
Tom: I decided to Facebook downsize after each school year.
Jerry: Yeah, I did some Facebook downsizing after I broke up with that whore Stacy. I didn't need her sorority Facebook stalking me anymore.