Explaining siphoning to a 5 year old

So, I was asked a question the other day about how a siphon works... Of course my mind starting thinking of words like hydrostatic pressure, gravity, and intermolecular forces. I was also told that I had to start at the beginning and explain as if I were talking to a 5 year old. Ok, so he or she is a very inquisitive and smart 5 year old... but a 5 year old none the less.

With that premise in mind, let me see what I can do.

Siphoning is really a principle of gravity. Which is what causes us to stick to the earth, and fall when we jump. I can't think of any other better explainable than that of a train. Let's picture a train going up a hill. It get's to the top of the hill and then starts down the other side. At any time it could turn off it's engine, and because the bulk of it's cargo is still on the downhill side, the train would begin to roll backwards. As it gets farther and farther over the hill, it comes to a point where even it turned off it's engine, it continue to roll forwards down the other side of the hill, even when some of the train still has to travel up the hill, there is enough weight on the other side that it will pull the rest of the train over. Now let's think of water as the train as it travels through a pipe. It's connected, just as the train is, not by metal connectors but by physical attractions between water molecules. When enough of the water is through the tube and down the 'other side' it will begin to pull the rest of the water through the pipe just as the train would pull the rest of it's cargo over and down the hill. So long as the water exiting the pipe is lower than the other side of the pipe where the water enters, gravity will pull the connected 'train' of water through the pipe.

Ok, so it's as simple as I could make it... but I'm still not sure a 5 year old would get the whole idea. Let me know what you think.