One of my favourite singers is Anita Belle Colton, better known to jazz fans as Anita O’Day. She adopted the latter name during the Great Depression, when she competed in dance marathons. She chose the name O’Day because it was ‘pig Latin’ for ‘dough’ — that is, the money she wanted to make.

Pig Latin originally meant incorrect Latin, and it was also called dog Latin or hog Latin. In the 19th century, it came to describe a kind of slang in which the first consonant (or consonants) of words are transferred to the end of those words and an extra syllable (usually -ay) is added. Thus dough was turned into O’Day. Give becomes ivgay and scratch becomes atchscray. If a word begins with a vowel, you simply add -ay (or sometimes -way or -yay) on the end, strangely turning essay into essay-ay and alley into alley-way.

Most pig Latin sounds like gibberish, but some words have interesting results when thus transformed. For example, the word be becomes eBay (the name of a well-known Internet trading site). Ayspray can be pig Latin for prays or spray.

Here are some more weird transformations created by pig Latin: Trash — ashtray Lover — overlay Trice — ice tray Wonder — under way Devil — evil day The Oxford English Dictionary includes the mainly American word ixnay, which is a pig Latin variant of nix, meaning to reject or deny (or as an adverb or interjection, meaning worthless or not at all). In the film The Lion King, Zazu says “Ixnay on the upidstay”, which means “Stop being stupid”.

The OED omits amscray, which is a common American variation on scram (= go away) but the editor, John Simpson, says it is being drafted for the revised edition.

Someone has already translated the Bible into pig Latin! The first verse of Genesis (or rather Enesis-gay) is: “In-ay e-thay eginning-bay Od-gay eatedcray e-thay eaven-hay and-ay e-thay earth-ay".

The French have a similar kind of slang called loucherbem. It originated among Parisian butchers and got its name from boucher, the French for butcher. Like pig Latin, it transferred the first letter of a word to the end, put a new letter — usually L — at the beginning, and added a new suffix (like -em or -uche). So boucher became loucherbem, and patron turned into latronpuche. This language is also called largonji, which results from the similar transformation of the word jargon.

Loucherbem is found as early as 1837 in the Memoirs of Vidocq, a criminal-turned-police-collaborator, who recorded Lorcefé for the Parisian prison La Force, where he spent some time.

Some of these private languages were originally devised so that a group of people (such as tradesmen or schoolchildren) could converse without eavesdroppers understanding them.

Such mysterious languages have been in use since the 16th century, when they were called ‘pedlar's French’. One well-known example is backslang, a variety of slang in which words are pronounced backwards.

Backslang was first used by London costermongers in the 19th century, and later caught on among butchers and others. A butcher might say to his colleague: “Evig reh emos delo garcs dene”, meaning “Give her some old scrag end”.

Backslang gave us the common word yob, which was originally slang for boy but has come to mean a lout. If you wonder why the police are sometimes called slops, it is an adaptation of backslang ecilop.

Backslang turned the numbers under eight into eno, oat, earth (or eerith), roaf (or ralph), evif, exis and nevis. This shows how words could be adapted by adding or removing letters or changing the pronunciation if they created problems when reversed. So shop became posh, butcher became richtub, balls became slabs, and head became deeache or dee-aitch.

Iona and Peter Opie, in their Lore and Language of Children (1959), give the example “Uoy nac ess reh sreckin ginwosh” for “You can see her knickers showing”.

The Opies describe several other ways in which secret languages are used to mystify or exclude outsiders. In Scarborough, they found teenage girls inserting ‘ag’ before each vowel, to make their own secret patter, or ‘thageir agown pagattager’. Children elsewhere used ‘eg’ or ‘arag’ in the same way.

Such secret languages have often been used by parents trying to prevent children knowing what they were talking about. In 1808, Elizabeth Grant wrote in her autobiography how parents had used a “how-vus do-vus language” until they realised the children had cracked the code, when the grown-ups adopted a new device of tacking ‘thegee’ onto the end of every word.

At least one such originally ‘secret’ expression has found its way into the OED: ‘F.H.B.’ ( = family hold back), which the OED dates from as early as 1911 and defines as “a colloquial intimation to the members of a family that their guests have first claim on the course or helping about to be served”.

Tony Augarde is the author of The Oxford Guide to Word Games (OUP, £6.99), The Oxford A to Z of Word Games (OUP, £4.99) and Oxford Word Challenge (OUP, £4.99).