This challenge involves a few well-known propeties of Diet Coke and Mentos.
Step One: Procurement
Buy, steal, or borrow Mentos, and several (plastic, not glass) bottles of Diet Coke. They can be bottles of any size, but keep in mind that the bigger they are, the more spectacular the... oh, but we're not to that part yet.
Step Two: Composition
Fact- When Mentos are placed in Diet Coke, they produce a reaction very similar in appearance to the carbonation that occurs upon the opening of a bottle of said beverage. Hypothetically, this reaction is catalyzed by the sudden release of pressure, which causes the carbon dioxide to rise to the top, taking the some of the liquid with which it was previously mixed along for the ride. My research indicates that we don't yet know why Mentos cause a more powerful version of this reaction, but that is irrelevant to this node, because we're just going to use it to our advantage.
Put one or more Mentos into a bottle of Diet Coke, then screw the lid back on before it spews out into thine tender countenance. The first time you try this, you will fail. Embarrassingly. Even if you have seen other people attempt it, even if you think you are somehow smarter or faster or have a better strategy than the other guy, you will fail. Clean your dripping, sticky face, and have another go.
Step Three: Catharsis
Providing you followed each step correctly up to this point, you are now among the Elite who have successfully constructed the fabled Mentos Bomb. This is an honor that few know exists, and even fewer have achieved, but it is not truly The Mentos Challenge.For this next step, feel free to place your flask of misery in any convenient place, e.g. A picnic table, your refrigerator, a vending machine (should you have access to the key), exchanged with a bottle in the cupholder of someone's car, or as a gift to your (select one: teacher/boss/enemy/friend/relative). My challenge to you is to place your little contraption in such a way that your target is unpleasantly surprised. Happy Hunting.
Disclaimer: I am not responsible for your stupidity. If you try this, and somebody gets hurt, I will not be held accountable in any way. You have been warned.