Told to me by an anarchist Scot friend of mine, this will enable you to render inoperable pretty much all bank machines (cashpoint/atm) used by UK banks in a matter of seconds. All you need is - a card the machine will accept, I don't believe it even needs to be in date. I'm not certain if it'll work on machines in any other country, so my childhood dream of annihilating CIBC may remain unfulfilled.

Step 1. Insert your card into the slot, about halfway in so the little motor starts and tries to pull the card in. DO NOT let go!
Step 2. Wait! The machine will try a few times to pull the card in, but of course you haven't let go, have you? Good. Notice it's just given up, and the screen is now displaying "THIS MACHINE IS NOT IN SERVICE".

Congratulations - the machine will now be worthless until the bank gets a technician out to reset it.

    Fun notes:
  • particular bank refused to give you a credit card for no good reason (in your opinion at least)? This is your revenge! Target their machines!
  • this has the potential for vast social experiments. You could disable every cash point on a street on a Friday night and watch the ensuing chaos.
  • although the machine probably can't read your card where you're holding it, the CCTV camera is probably looking at you - so a spree of disabled machines might arouse suspicion and your dumb ass would be using each machine just as they broke. So if you're going to try the first idea, get some buddies to join your conspiracy.

DISCLAIMER: Don't be an asswipe about this. This can be a cool party trick to impress friends, but with great power comes great responsibility, so don't abuse this power because you'll be inconveniencing dozens of people if you just busted the only machine for miles. In fact, as Troy McClure says, now that you know what to do, don't do it! *Laughs evilly, Zorak style.*