I once won a secret sound contest. Slap your hand on the table twice and you'll get an idea of what the sound was. It didn't sound like anything at all.
It had been running for just over four weeks then one day somebody said, "It's somebody snapping the locks on a suitcase." The announcer said, "Ooh, I thought you had it then." And a couple of days later he said, "Here's a clue. It's something that has been out of fashion but now it's back in again."
I grabbed the phone and said, "It's somebody snapping their braces." Easy peasy, but I'd never have guessed it from the sound alone.