A man sits down at a bar and orders a double martini.
After he finishes, he peeks inside his shirt pocket, then orders another.
After he finishes that, he again peeks inside his shirt pocket and orders another double martini.
The barman says: "I'll bring you martinis all night but why do you look inside your shirt pocket before you order a refill?"
The customer replies: "I'm peeking at a photo of my wife.
When she starts to look good, I know it's time to go home."