Change oil!

[Johnn]

A frail old man and his pregnant young wife arrive at the hospital. She gives birth to a healthy baby boy.

"I'm surprised you got her pregnant at that age" the nurse said.

"Just gotta keep the motor running" replied the old man.

The next year the arrive again this time giving birth to a healthy girl. The nurse again is surprised at him.

"My secret is to keep the motor running" he said again.

The next year again he arrives and again they have a healthy baby boy.

"Like I said. Just got to keep the motor running" said the man.

This time the nurse says "Well change the oil you daft bastard, this ones black.

[Acro]