Knows when to stop

A man walks into a bar and orders one shot. Then he looks into his shirt pocket and orders another shot. After he finishes, he looks into his shirt pocket again and orders another shot.

The bartender is curious and askes him "every time you order a shot, you look in your shirt pocket. Why?"

The man replies, "I have a picture of my wife in my pocket and when she starts to look good, I go home."