Question: There are 3 switches downstairs, each corresponding to one of the light bulbs upstairs. How can you figure out which light switch goes to which light bulb by only making 1 trip upstairs?
Answer: You turn on one light bulb. Leave it on for a while. Then, turn that one off and turn another one on. Go upstairs. One light bulb will be cold, one will be warm, and one will be on.
Question: Your friend tells you about a story he once tried to impress a young lady with, but instead got a slap in the face. He wants you to attempt to see the flaw: It was a hot and windless day, in our bunker, when suddenly one of ours yelled: "Enemy!" We opened fire on them, leaving one hundred of them dead before they retreated. I was checking a dead captain's glasses when the shout came that they were incoming again, and the CO ordered us to open up on them with our mortars, when I yelled: "Cease fire! They're Americans!" Later, an American colonel thanked me for my work after I said that I saw their flag, waving back and forth in the wind. What is wrong with this story?
Answer: At the beginning, it was said that "It was a hot and windless day," yet at the end, it is said that "The flag was waving back and forth". Had it been windless, the flag would have been limp.