Cucumber trick

Someone else please tell me they know this trick of getting the bitterness out of cucumbers? I can't remember where I learned it...either from my mum or from some girl at school. You cut a small slice of one end and rub the cut surfaces vigorously together and it draws out the bitter latex from the skin. Presumably the latex dries and becomes sticky on contact with the air so it sticks to itself. Works a treat, but several other people I've asked had no idea.