dory flop

When an uncircumscised man with a syphilis chancre retracts his foreskin, the entire ulcer flips out all at once because it is too hard to bend. This resembles the movement of a broad-beamed skiff or dory as it is turned upside down.

Good thing I kept the lights on with that guy. I saw that dory flop, so I grabbed my clothes and got the hell outta there.