A person who posts obscene amounts of memes of Facebook and/or tumblr, consequently clogging your activity feed (see spam).
Guy 1: hey, i think i should add Belle's as a friend on Facebook
Guy 2: nah mate, watch out, she's a meme fiend!
Guy 1: a what?
Guy 2: a meme fiend-you'll be spammed by her endless amounts of Internet venality!
Guy 1: oh...but she's hot.