Friends of mine have a four-year-old boy.
One night, after the boy went to bed, they felt like fulfilling their marital duties. After they were finished, the wife wanted to go to the bathroom. She was startled to find somebody in front of the door: the boy was sitting on a chair besides the door to the bedroom.
"What are you doing here?!?" she asked.
The boy replied without missing a beat, "Waiting for you to finish."
Decent boy.