According to Wentworth & Flexner's Dictionary of American Slang, pig Latin been around since the 1770s. It's a made-up language game beloved of eight-year-olds and linguistics students. Also known as hog Latin and dog Latin, it offers a perceived cloak of protection - there's a certainly a touch of 1960s Enid Blyton about it. It's a perfect tool for getting a message to a fellow gang member without the adult present understanding what you're going on about.
How to Speak it
If you're in the know about pig Latin, you're in the gang. The great thing about speaking pig Latin is that it's not simply a question of learning a new vocabulary and a complicated set of grammar rules. It sounds vaguely like Latin, but really it's English with letters rearranged with the sound 'ay' stuck on the end.
For words that begin with a vowel, just add 'hay' to the end of the word.
For words that begin with a consonant, put the consonant at the end of the word, and add 'ay' on the end of that.
For words that begin with two or more consonants, put them at the end of the word and add 'ay'.
For short words like 'and', 'the' and 'in', don't bother translating them.
Simple as that. There are several variations to these rules, and you can make up your own to make your version even more 'secret'. Or you could apply the same rules to a different language.
The following is the first two stanzas of a well-known poem by Ewislay Arrollcay. See if you can work out what it is.
Astway illigbray, and the ithyslay ovestay
Idday yregay and imblegay in the abeway:
Allhay imsymay ereway the orogovesbay,
And the omemay athsray outgrabehay.
'ewarebay the Abberwockjay, my onsay!
The awsjay that itebay, the awsclay that atchcay!
Ewarebay the Ubjubjay irdbay, and unshay
The umiousfray Andersnatchbay!'