a shake of the head

Rigby has been shaking her head "no" now for some time. I think she is just now realizing shaking her head means "no." for example, at dinner when she does not want any more to eat she shakes her head "no." of course we don't listen to her, and try to feed her the rest of her dinner, but it is much more difficult from that point on. we are trying to teach her to nod "yes." this is very funny. she tries and in doing so she thinks she has to move her whole body to get her head to move up and down. it is funny and we laugh, then she laughs.