"How long before I can get a haircut?" joke

A guy sticks his head in the barber shop and asks "How long before I can get a haircut?"
The barber looks around the shop and says, "About 2 hours."
The guy leaves. A few days later, the same guy sticks his head in the door and asks, "How long before I get a haircut?"
The barber looks around the shop full of customers and says, "About 2 hours."
The guy leaves.
A week later, the same guy sticks his head in the shop and asks, "How long before I can get a haircut?"
The barber looks around the shop an says, "About an hour and half."
The guy leaves.
The barber looks over at a friend in the shop, and says, "Hey Bill, follow that guy and see where he goes." In a little while, Bill comes back into the shop laughing hysterically.
The barber asks, "Bill where did he go when he left here?"
Bill looked up and said, "To your house."