The Diet Coke and Mentos experiment has received major airplay on shows like MythBusters and Unwrapped, so many permanent kids try to do it themselves. This is the funniest example of the Mentos bottle rocket I've ever seen, and because we're sadists it will probably go viral within the next week or so.
Enjoy! (nerd moment below)
How does this work? The Mentos have an inconsistent, porous surface, which permits much of the CO2 (which Diet Coke has more of than other American sodas) to park in them. This increased surface area for a potential reaction is the major reason why old-school Mentos work better than the glossy varieties. On the way down, even more gas is produced by the CO2, as well as by the reactions between the Aspartame and potassium in the soda and the gelatin and gum arabic in the candy. By the time the candies have sunk to the bottom, there is so much gas pressure that it must escape, producing the pretty little waste of processed food known as the Diet Coke Cannon.