Three scientists were sailing across the ocean, when their boats gas ran out, and they were washed upon a random island. They decided to go exploring, so that they could figure out how to get off the island. While exploring however, they came across a group of cannibals, and were captured. The cannibals told them: "Bring us 10 of one kind of fruit, and we'll release you."
So off went the three scientists. Soon, the first scientist came back. He came back with 10 strawberries. With smiles on the cannibals faces, they then told him: "You must shove these fruits up your butt without showing any emotion. If you do this, you are free to go." So away he went. One. Two. Three. Four. On his fifth, he slightly squinted in pain, and was killed. Poor guy.
Along came the second scientist. He had ten blueberries. The cannibals told him the same thing, though quite sad as they believed he would be able to complete the task. So away he went, shoving them up his butt. One. Two. Three. Four. Five. Six. Seven. Eight. Nine. On the tenth, he burst into laughter. Needless to say, they killed him.
Now, in heaven, the first scientist said to the second: "Why did you burst into laughter? You could have lived!" The second scientist replied: "I saw the third scientist coming with pineapples."