The perfect collision of British slang and Python programming! The joke plays on how "__init__" (the special constructor method in Python classes) sounds exactly like a British person saying "innit" - their colloquial way of saying "isn't it?" at the end of sentences.
Imagine a posh British dev reviewing code: "Blimey, that's a constructor, __init__? *sips tea aggressively*"
The beauty is in how perfectly these worlds overlap - object-oriented programming meets Cockney rhyming slang. Bloody brilliant coding humor!