the literal meaning is what the fuck is up. it can be used as a question, greeting, or interjection.
Ana:(to friend) Hey look its that hottie kyle
Kyle:(to me) Its that bitch ana again
Ana: hey kyle, how have you been?!
Kyle: WTFIU!
Kyle:(to me) Its that bitch ana again
Ana: hey kyle, how have you been?!
Kyle: WTFIU!
by Chode Trickery May 5, 2011
Get the WTFIUmug.