A wino walked into a bar one day, and started begging for drinks.

One of the patrons tells him he'll buy the bum a drink, but
first he has to take a drink from the spittoon over in the corner.

The wino is in a bad way, so he takes the guy up on his offer, goes
over and picks up the spittoon, raises it to his lips, and starts
chugging away.

The guy at the bar, who didn't really believe the wino would take
him up on his offer, is horrified. "Stop! Stop!" he yells, "I'll
buy you a drink now!"

But the wino keeps on drinking from the spittoon.

Again the guy at the bar calls out, "Stop! Put the spittoon down!
I'll buy you a drink!"

But the wino keeps on drinking. Finally, after about five minutes
he stops, and puts the spittoon down.

So they guy at the bar says, "Hey, didn't you hear me telling you
to stop? Why didn't you stop?"

"I couldn't," the wino replies, "it was all one string."