One of the earliest signs I taught Connor was "eat" and "drink". They're very useful signs and very easy to teach because there is no motivator like hunger. (Money hasn't quite entered Connor's realm of thought yet)
On our first night in Luz, Connor refused his dinner. He'd not been eating well that day as well as we were travelling. It was very frustrating trying to feed him and having him just clamp his mouth shut or spit everything out. Finally I gave up and put him to bed. I thought he'd wake up multiple times in the night crying for milk but he didn't.
The next morning, Dear Hubby and I were woken up at 6am by our little monkey. "Mummy, Mummy!" he said and signed "Help". I replied "Yes Connor, Mummy will help you. What do you want?" He said again, more desperately this time "Mummy!" and in quick succession signed "eat" and "drink".
We burst out laughing. Dear Hubby said "Well I guess someone is finally hungry!" And he was. He ate a whole lot of cereal and yoghurt that morning.