Alan, Jim and Bob are jungle explorers. One day they suddenly find themselves surrounded by fierce spear-wielding cannibals. The leader of the cannibals tells them they may go free if they pass a test of endurance. If they refuse or fail, they will immediately be killed and eaten. Faced with little choice, the three explorers agree.
"What's this test then?" asks Alan.
"Each of you must go out into the jungle and return with nine pieces of fruit," replies the cannibal chief. Alan, Jim and Bob don't think this sounds too bad, so off they go.
First to return is Alan, carrying nine apples.
"Now," says the cannibal chief, "you must push them up your XXX without your face showing any discomfort or emotion."
Alan gives it his best shot, and manages to get one apple up there, but on the second attempt he winces, and is immediately killed.
Next back is Jim, carrying nine grapes. The cannibal chief explains the second part of the test to him. Jim manages to get eight of the grapes inserted without a problem, but on the ninth he bursts out laughing and is killed on the spot.
He reaches the pearly gates to find Alan waiting for him.
"What on earth are you doing here?" asks Alan. "Grapes should have been easy!"
"I know," said Jim, "But then I saw Bob coming back with all those watermelons..."