A man walks into a bar, takes a seat, and asks the bartender for three shots of gin. The bartender gets one shot of gin and sets it in front of the gentleman.
"I'll take all three right now, if you don't mind," says the man. He puts $20 on the bar.
The bartender puts down two more shots of gin and picks up the $20. He watches from the far end of the bar as the man slowly sips the three shots of gin, one after another, pondering and lost in thought while he drank. After the third shot he thanks the bartender and leaves.