This is a riddle: It is night time in your bedroom and the light has broken. You are getting dressed and need a pair of socks. You have got 10 red, 8 white and 12 grey socks in a drawer- how many do you have to pull out in the dark before you know you have a matching pair?

Four will ensure you've extracted at least two of the same color - but unless you turn the light on there's still no guarantee that you'll get two of the same color on you feet. Is that why it's a riddle?