Sheila

As well as being a female name, Sheila is a slang term for a woman, it's generally used in Australia as the word "bird" is in the UK.

Here's a completely unrelated but great English tune:

Johnny

Johnny is not only a shortened verison of the name Jonathan but also slang for a condom. This slang term has quite an interesting history, it comes from "Johnny Frenchman" a term used to speak about French people.

A condom was at one point known as a French letter, the reason for this is that the condom gets its name from Colonel Condom one of Britain's Royal Guards who improved it to protect his forced from the saucy French. It was known as a French letter (the French called it an English letter), later a Frenchie and finally a Johnny from Johnny Frenchman!

As you can see in Allo! Allo!, our point of view hasn't really changed!

Adam and Eve

"Would you Adam it?" Adam and Eve are not only the biblical characters, the creators of the human race but also cockney rhyming slang for the word believe, so by saying "Would you Adam it?" someone means "Would you believe it?"

Ayrton

If someone says "Can you lend me an Ayrton?" then you may be a little bemused but it's a 90s development on cockney rhyming slang with F1 legend Ayrton Senna meaning tenner which in turn means £10.

Here's a Youtube montage of the man himself:

Barbie

Barbie is of course not only the infamous blonde doll but is also the short version of the name Barbara. However, it means something completely different in the following sentence: "We're having a barbie tonight. Perhaps you'd like to come round?"

Barbie is short for barbecue which is also often called a BBQ, considering the lack of sunny days in the UK, it's more commonly used in Australia and New Zealand. For some more Aussie words, you might enjoy the following video!