Further shortening of FFD (acronym for Fat Fucking Disgrace).
"Look at Kid Fifty over there" (indicating a fat black kid with man boobs from eating too much candy)
"Wow. Check out the comment from Shirtless Doug Fifty!" (indicating a comment left on a busty girl's Myspace page by a fat, shirtless man from Ohio that contains both numerous references to sensuality, and numerous spelling and grammatical errors.)