How long before I can get a haircut?

A guy stuck his head into a barber shop and asked, "How long before I can get a haircut?" The barber looked around the shop full of customers and said, "About 2 hours." The guy left. A few days later the same guy stuck his head in the door and asked, "How long before I can get a haircut?" The barber looked around at the shop and said, "About 3 hours." The guy left. A week later the same guy stuck his head in the shop and asked, "How long before I can get a haircut?" The barber looked around the shop and said, "About an hour only." The guy left. The barber turned to a friend and said, "Hey, Bill, do me a favour, Follow that guy and see where he goes. He keeps asking how long he has to wait for a haircut, but then he doesn't ever come back." A little while later, Bill returned to the shop, laughing hysterically. The barber asked, "So where does that guy go when he leaves?" "To your wife."