Via the Fermat's Library, a paper that describes a really strange mathematical result:

  • Write two distinct numbers on slips of paper and give them face down to a friend.
  • Your friend chooses one slip at random and looks at the number written on it.
  • They are now asked to guess if the number on their slip is greater than the number on the other slip.
  • The surprising result: There is a strategy that allows them to guess the right answer with a > 50% chance of being right.