A guy and his son go into a bar. The son is a miracle of nature and is just a head. The man asks the bartender for two shots. The man takes one shot and gives the other one to his son. The son swallows down the drink and out pops an arm.
The man thought, "Hey this is good."
So he asks for two more shots. He drinks one and gives the other to his son again, and out pops another arm.
The man the asks for a double and gives it to his son. The son throws it down and suddenly explodes.
The bartender looks over at the man and says, "Looks like he should have quit while he was ahead."