It was a beautifully simple plan - creep into an abandoned house next to a bank after dark, spend the night knocking a hole through the wall into the vault, and sneak away with bagloads of cash before dawn.

But removing bricks is one thing, doing so in the right place quite another. After crawling through the hole, the thieves in Mexico City found they had miscalculated. Instead of emerging in the bank, they were face to face with a toddlers' slide. So they began hammering again, this time through two walls, from inside the children's party venue just behind the bank.

But when they finally climbed into the bank the euphoria can't have lasted long. They were not in the vault, but in the toilet. And not only were they looking at urinals rather than wads of cash, they were locked in, and the alarm had gone off.

Their heist a mess, the would-be robbers scrambled back through the holes they had so carefully made and disappeared, without a peso for their efforts.