"Always turn the light on First" joke

There was this guy who always went out drinking with his friends. He would always come home very late.

One night, while he was at the bar he told them his secret for being able to sneak in late. "When I walk in the house, before the wife can say anything, I lay her down, take off her panties, and give her the best oral sex she's ever had, until she has such an orgasm that she falls into a deep sleep. Then, I wash up and go to bed. By morning, she is so pleased, she doesn't care what time I came home."

One of his friends thinks this is a great idea. So he stays out late, comes home, sneaks into the bedroom, gives his wife the best oral sex she's ever had, and goes to wash up.

His wife walks into the bathroom, obviously upset that he's home so late.

"Hey, why aren't you sleeping?" he asks.

"I was was, but I came in to tell you that we've got to sleep on the couch tonight,' cause my mother is sleeping in our bedroom."