Really have to go to the bathroom, with no bathroom. There's always a tree or something.... unless, you know, you're locked in a closet or whatever.
The large boiler on the front of the Cugnot served as its engine, but besides visibility, there was always the problem of the hot copper pot burning or parboiling its passengers with super-heated steam or simply exploding from the intense pressure. The vehicle went a whopping two miles an hour and on its initial test run went out of control and knocked down a low stone wall.
More here.
Elephantiasis or leprosy?