A drunk gets up from the bar and heads for the bathroom. A few minutes, a loud, blood curdling scream is heard. A few minutes after that, another loud scream reverberates through the bar. 

The bartender goes 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," slurs the drunk, "and every time I try to flush, something comes up and squeezes the hell out of my balls." 

With that, the bartender  looks in and says, "You idiot! You're sitting on the mop bucket!"