Mr Poopy Goes To The Toilet
Mark quipped this made up title in response during an interview where Dutch filmmaker Anton Corbijn talked about the liberal portrayal of toilet use in Dutch films. Years later the Good Doctors mistakenly referenced Mr Poopy as something mentioned in the review for Jackass 3.
Thankfully no one has as yet made a movie out of this joke (see Benjamin Sniddlegrass).
For Simon's own poopy toilet anecdote, see Try Hard.