Einstein sits next to a man during a long trip. Einstein says, “Let us play a game.” I’ll ask you a question, and if you don’t know the answer, you’ll pay me $5; if I don’t, I’ll pay you $500.” The man agrees, and the game continues. Einstein’s first query is, “What is the distance between Earth and the Moon?”

The dude doesn’t say anything. He digs inside his pocket and takes out $5. He then asks Einstein, “What climbs a hill with three legs but descends with four?” Einstein thinks about it for a long time but cannot answer the question.

After nearly an hour, he hands the man $500. An furious Einstein then asks, “So, what goes up a hill on three legs and down on four?” The man reaches into his pocket and hands Einstein $5.