MilkmanDan says... I think that's correct, or at least I've heard that explanation also. I probably heard it discussed on the BBC show QI? I guess that would make it sort of like Pig Latin, although at least to me it seems like the barrier to entry into the "in" group of Cockney rhyming slang is massively higher than the one for Pig Latin. ChaosEngine said: From my understanding the whole point of rhyming slang was obfuscation. The idea was to be able to communicate in plain sight while "outsiders" (police, upper class, etc) missed the true intent, although this mostly speculation.