There is a verse from the bible that I now understand a little better. To paraphrase, it says let your yes be yes and your no be no. I may need to teach my younger grandson this one.
Little Roman, at a year and a half, now emphatically shakes his head no and says "No" when you ask him a question like, "would you like juice"? He then is unhappy when his twin sister gets juice and he doesn't! Funny kid.