‘Allo me Chinas! This week’s Cockney rhyming slang is Aris.
Aris is Cockney rhyming slang for buttocks, but it’s a bit more complex than your usual Cockney, because it makes use of double rhyming and truncation, which further obfuscates the original word.
Bottle & glass became rhyming slang for arse, which is shortened to bottle. Aristotle then becomes rhyming slang for bottle, which is truncated to Aris. Thus, Aris is rhyming slang for arse.
Now you may be wondering, “Why choose ‘buttocks’ and not ‘arse’/’ass’ then?” That has to do with the British use of “arse” and “ass”. In British English, the two words are not interchangeable. “Arse” is referring to the “buttocks”, while “ass” is referring to a “donkey”. In American English, there is only one word, “ass”, so to be clear I further expanded the rhyme to its logical conclusion — like I did with Jodrell and ice cream, as wank and geezer aren’t part of American lexicon.