Is Opposite Day a Paradox?

I used to annoy my classmates so much with this in the first and second grade. They'd be like 'it's opposite day.' And I'd say 'if it's opposite day then it's opposite so it's not really opposite day.'

Literally at least once a week in my class we have this arguement.

That's how I explained paradox's to my brother.

That's why Opposite Day doesn't exist it cancels itself out.

No because if it weren't Opposite Day you wouldn't say or worry about that. It's opposite day

Yet another eternal paradox !!

It's not opposite day- it really is
It's is opposite day-it isn't
You would have to say it isn't to say it is but you then you need to declare that with it's not opposite day then you have to declare that with it's not opposite day and the cycle continues therefore creating a paradox