Back slang is an English coded language in which the written word is spoken phonetically backwards.
Back slang is not restricted to words spoken phonemically backwards.
An example is trousers and its diphthong, ou, which is replaced with wo in the back slang version reswort.
[1] In 2010, back slang was reported to have been adopted for the sake of privacy on foreign tennis courts by the young English players Laura Robson and Heather Watson.
[2] Other languages have similar coded forms but reversing the order of syllables rather than phonemes.