the best homemade "pop-bottle bomb"
This is a little more extreme than dry ice. I live out in the country so its not a huge problem, but I'm going to remind everybody this is DANGEROUS. <--- disclaimer.
1. Get a 20 ounce pop bottle
2. Muriatic (only this) acid. It's used for cleaning swimming pools, and you can get a jug of it at a hardware store.
3. Aluminum Foil
Take a 5 inch by 5 inch square, and fold it up, so you make a little aluminum foil stick. fold this in half so it makes a little U shape.
Stick this in the pop bottle. Then when you're ready, pour about 4-5 ounces of the acid in there. Don't get this **** on your hands or anywhere near your face. Seriously. Don't breathe it in either. Please. Put the cap on and THROW the thing as far as you can. The 20 oz bottle will expand to about the size of a 2 liter bottle, and it will make a huge BOOM. Get some gloves to pick up the remains. Don't set this off near anything flammable, as the reaction produces hydrogen gas. Unless you want to see a huge flame-ball (from a safe distance of course)
Muriatic acid is dangerous. It is used to strip dirt, black tire marks/tar, and other things that stain out of concrete. It does a very nice job. It'll do a nice job on your hands, eyes, mouth, well, you get the point.