Okay, it was inevitable. I had to get to this subject eventually.
Yes, it works wonderfully.
Take a 3 litre plastic bottle of Diet Coke outside. It's very, very important that you do this outside. And you use a diet soda to avoid attracting ants.
Pour-off the soda carefully, without shaking, until the top of the soda in the bottle is below the narrower part of the bottle. You don't shake the bottle to avoid losing fizz. And you lower the level of the liquid in the bottle because we are going to be dropping in multiple Mentos, and having the soda a little bit below the neck minimizes the odds that any of the Mentos will be fired-out of the bottle.
Put the bottle in the middle of the lawn, away from people, away from the house. You put it on the lawn so that the ground will absord the fountain, and away from the house that that you won't discolor anyone's property, and away from people so that they won't be wet, or hurt by the fountain. (I doubt that soda in the eyes is a good thing.)
Make sure your hands are very dry. Take 5 Mentos out of the package, and stack them carefully between your thumb and index finger. You make sure that your hands are dry, so that the Mentos won't stick to your skin. You stack them carefully so that yon can make all 5 fall at the same moment into the soda.
Position the stack of Mentos over the bottle opening, drop them all in at once, and run.
The soda will come surging-up out of the bottle and shoot about 12 feet into the air.
The reason why this works seems to be that calcium "pills" like Mentos are covered with "zillions" of microscopic nooks and crannies called "nucleation sites" which form "nucleuses" or center points for gas trapped in the soda to begin escaping and forming bubbles.