-1 plastic bottle with screw on lid(YOU MUST HAVE THE LID!(size doesnt matter...the bigger the better though). Get this anywhere.

-Water. Get this from the sink.

-Dry Ice. If you have an icecream man ever go by your house ask him if you can have a chunk of Dry Ice....if he asks say you guys are having a picknick and need it for cooling of Hamburger or something. They usually will give it.

Assembly

Take your Plasic bottle and fill it up about a quarter the way with water (thats how i like to do em) the less water the more time but the louder, you can put more or less in though...up to you. Get the dry ice slide a couple of into the bottle (as long as they can fit in the bottle they will be big enough) then Immediatly put on your lid (SCREW IT ON TIGHT. Throw it somewhere or get far away from it (due to plastic shrapenal) and wait 4 or 5 mins (DO NOT GO LOOKING FOR IT IF IT DOESNT GO OFF!) and BOOM it is really loud! i mean loud.