My friends son was like Jojo's dd..he said no to everything. lol
Another friends daughter and my Ds3 said yes to everything when they were one. My friend one day asked her dd if she wanted doggie poop to eat and she said yes.
My dh would ask our son if he wants a beer and crack up laughing when he said yes
Of course now my ds3 has switched and is saying no to everything
But it is really funny because you can almost see the look in his eyes when he has realized that he just said no to pizza or candy. Now he usually waits to hear the question before belting out a no.
I think whatever word they hear alot they tend to repeat when they are 1. And no is a very common one