16 Oct

coin flip trick

This is a “rounds” trick for deciding who buys the round when you’re drinking with two friends. You won’t win all the time, but your drinks bill will be cut by 25%.

You’ll need an accomplice and a victim (the person you want to pay for the drinks). The only instruction to the accomplice is that when your left palm is up, bet ‘heads’. otherwise, bet ‘tails’.

  • flip a coin with your right hand.
  • your left hand should be turned randomly palm up or palm down.
  • as the coin comes down. slap it onto the left arm with your right hand (in the usual manner) such that no-one knows what it is.
  • if the palm is up, you and your accomplice say ‘heads’. otherwise say ‘tails’.
  • if all calls are the same, do the toss again.
  • if the victim gets the call wrong, he pays for 3 drinks. otherwise, you and your accomplice buy 1.5 drinks each.

On average, you and your accomplice will pay for .75 drinks per round, and your victim will pay for 1.5 drinks per round.

You can also do this with cards. shuffle a deck and remove one card face down. bet on whether it is odd or even. As long as you and your accomplice always bet the exact same, the drinks payment ratio will be the same even though you only ‘win’ 50% of the time.

On reflection, 25% is not an amazing saving, but those are the thoughts that I go to sleep with…