snopes.com: Bottle Bombs
If you mix Drano and foil inside a bottle, then shake it, it will create an explosion big enough to sever your fingers and give you 2nd and 3rd degree burns. The shaking is what starts the chemical reaction, i.e. picking it up.
This youtube vid is on that snopes page:
...just over a month ago and I've lost about 7 or 8 pounds in that time. At first I attributed the weight loss with being sick for a couple weeks, but I've been back to normal for about a week and a half and the weight is still coming off. Pretty fucking cool! :yesway: