You know wrong, then.
It comes from Greek. The plural has never been octopi in any language.
( Newington, Sat 28 Jul 2007, 13:30, archived)

i use the word octopii
i will continue to use that word

you word nazi
( minimum fuss - an all time favourite, Sat 28 Jul 2007, 13:32, archived)

I hate to break it to you, but the greeks never invented octpusses.

( G/PP 💩💩💩💩💩&#128, Sat 28 Jul 2007, 13:33, archived)