Joke

Dr. Jackson was almost finished making the incisions. All that remained in the tricky bone-marrow transplant was to insert the donated material, and still no sign of Dr. Jackson's eldest son, who was supposed to assist in the operation. "Where the Hell is Paul?" Jackson mumbled to the nurse. "He's in the break room, Doctor. He said to page him when you're ready to perform the transplant."

"Oh, I see," said the Doctor. "The son will come out to marrow."