A drunk gets up from the bar and heads for the bathroom. A few minutes later, a loud, blood-curdling scream is heard from the bathroom. Then, nothing.
 
After another minute or two, another loud scream reverberates through the bar. The bartender goes into the bathroom to investigate why the drunk is screaming.

"What's all the screaming about in there?" he yells. "You're scaring my customers!"
 
"I'm just sitting here on the toilet minding my own business," slurs the drunk, "and every time I try to flush, something comes up and squeezes the hell out of my nuts."

The bartender opens the door, looks in, and says,

"You're sitting on the mop bucket.''