Hmm, is that octopi as in octopie which my grandmother could quickly cut into eight equal slices–her slice being the biggest? Or, is that octopus as in the slime that oozes from an eight sided sore? Or, is it octopus as James Bond (and I) would refer to in its plural as octopussies.
My general solution to this problem (the truth is that I have no idea, I usually tell my students that is a very rude word) is to use the singlular as an antecendent in my conversation. For example:
Hey, guess what I had for dinner last night!
I dunno, what did you have?
We had them eight legged things, you know?
Eight legs? Nope, I don’t know.
Well, thems called an octopus! Yep, we had six of 'em.
The waiter charged us for six octopussies and I told him that we hadn’t ate no octopussies, or any pussy at all in his joint, and that all we had was a bunch of slimey shit that tasted like dead fish on a big plate.
He got really teed off and called the cops and told them that we come into his joint and ate their eight legged pussies all evening and didn’t want to pay.
We told the cops we was teachers from Taiwan, and they just laughed and told us to go home and quit hustling the local restaurants for eight legged pussy.