Pressure/Push activated valve

My wife asked me today if it would be possible to install some sort of pressure/touch activated hose bib type outlet outside our house for our 2 1/2 year old daughter for water play. I've seen something like I'm thinking of for cattle/livestock feed, where drinking pushes a lever which activates a valve letting in more water. Ideally it would be something that would attach to a hose bib, as it's not worth a whole big installation to me. Any thoughts?

At any pet store, you can get a screw on dog watering device. They nuzzle a stem with their nose to get a drink