can you oridnary day an ordinary day?

This response is made with the assumption you are playing in a multi-player game...

Yes. It won't cause any other BFC to return though. Once a BFC has been cancelled, it's over and done with. You will just be removing THAT PARTICULAR Ordinary Day from play. And the end result is, there's still an Ordinary Day in play.

here's an interesting addition to your question...you can even use Ordinary Day to cancel itself.

in a tournament, both players use the condition at the same time. Let's say you pick ordinary day and your opponent picks something else. You decide that the player's BFC would benefit you more than it would hurt you. you can choose for your Ordinary Day to cancel itself.

-Rob