On the TV show I had fun demonstrating little known tools like this little plastic gadget that slips up the backside of any tube, be it toothpaste or glue. It prevents anything from moving back down the tube and can even be used to smoothly push stuff out the other end. It is called a "Squeezit".
Personally it can stop a lot of maritial fights about where to squeeze the toothpaste!
I got mine from Storage Works in Calgary, Alberta for about $5 each.