Jock male/female chauvinists fantasizing over fannies(butts) in ghetto street talk fashion. A blending of the words "fantasizing" and "fanny" creating "fannysize". Any play on the word fantasy that leans to anything sexual.
Ted says to Harry regarding Gina's bum,
"I'd like to drive it home". Harry replies, "keep on fannysizing!"
"I'd like to drive it home". Harry replies, "keep on fannysizing!"
by cYask8 April 11, 2009