"Octopi" is only "correct" because of common usage. Octopus does not have a Latin origin, so it doesn't make sense to pluralize it that way. Which is to say it's not technically correct, it's just "correct".

In the proper format of this meme, the wojack in the middle should be obsessed with technical correctness, while the one on the right is fine with merely "correctness" (as in, enough people use it to make it understood).

But since you can understand it, the format is merely "correct" (I'm being tongue-in-cheek to make a point)