Operation

This ageing man was on the operating table awaiting surgery and he insisted that his son, a renowned surgeon, perform the operation. As he was about to receive the anaesthesia he asked to speak to his son.

"Yes Dad, what is it?"

"Don't be nervous, son, do your best and just remember if it doesn't go well, if something happens to me... I've left instructions

Spoiler:

for your mother to come and live with you and your wife..."