Another idea is baking soda vinegar bombs which im sure in one form or another everyone has done. Its alot safer and still fun. Me and my friends toss them around to scare ppl and stuff. You fill like a 20 oz. bottle half with vinegar and then you rap baking soda in a paper towel then drop it in and cap it and shake it up. It better because it builds tons of pressure but you dont have the risk of it blowing up in ur hand or i have never had one do it and we had them sitting around forever.