London ? You’d better get ready to use your loaf if you want to get your hands on some bread.

Over the next three months a cluster of East London ATMs will be offering customers the chance to withdraw cash using written prompts in Cockney rhyming slang, the area’s colorful and often impenetrable dialect.

ATMs run by a company called Bank Machine offer a language option allowing customers to enter their “Huckleberry Finn” instead of their PIN, and rather worryingly informs them that the machine is reading their “bladder of lard” at a prompt about examining their card.

The origins of Cockney rhyming slang are obscure. It is thought to have been used by market traders who needed a way of communicating without tipping off their customers.

It works by replacing a word with a short rhyming phrase. For example: “Money” becomes “bread and honey,” which in turn is shortened to “bread.” Similarly, “head” becomes “loaf of bread,” and then just simply “loaf.”