NO spells no!

I thought the "no" stage had ended. Unfortunately, Cohen is beginning to spell and has learned to spell "NO." So now, every time I ask him to do something he says "N.O. That spells no."

Me: "Cohen, will you bring me the remote, please" Him: "N.O. That spells no. I won't do it"

Me: "Cohen, come eat." Him: "N.O. That spells no. I won't do it."

I mean we go on and on like this. ALL. DAY. Sometimes, this predictable response backfires on him. Yesterday I said " Come on, let's go outside." He says "N.O. that spells no. I won't do it. Oh, wait mama, I mean I do want to go outside. How do you spell yes?"