You have 12 black socks and 12 white socks mixed up in a drawer. You’re up very early and it’s too dark to tell them apart. What’s the smallest number of socks you need to take out (blindly) to be sure of having a matching pair?
Answer: 3 socks. If the first sock is black, the second one could be black, in which case you have a matching pair. If the second sock is white, the third sock will be either black and match the first sock, or white and match the second sock.