Rusty

“Doctor, doctor, I’m so worried,” said the anxious man.

“Both my wife and I have black hair, but our son’s just been born with red hair.

Do you think something funny has been going on?”

“Not necessarily,” replied the doctor.

“How many times do you make love?”

“About 5 times a year.”

“Well, there’s your answer then, you’re just a little rusty.”