Y Cookie?

I'm attempting to set boundaries for Ari but it is so hard! He sees me eating a cookie, and he wants a cookie! He's got his debate down to a science. He says:

"Cookie?"

And then I say:

"Okay, one cookie."
"Y cookie." He confirms. "Y" meaning "one." In case you don't speak "Ari-ese."

After scarfing down "y" cookie, he says:

"Cookie?"

And then I say:

"You just had one cookie. That's it!"

His response:

"One cookie?" He looks at me with pleading eyes.

This kid is good.