Fu-Fu...This came to me (pun intended) in highschool in the form of the this sing song I created...
"Want to see my Fu-Fu hopping through your forest? Pull out a condom and pop it on his head." Sung to the tune of Little Bunny FuFu. Get it?
It actually hasn't been referred to as Fu-Fu for a long time
An ex of mine liked to call it that, and I named her vagina Fi-Fi, which she liked a lot.