Quest for Fire
A soda pop can, a candy bar, and the sun. Supposedly, that's all you need to start a fire by using this technique here. Essentially you use the chocolate to polish the concave bottom of the pop can. Once you have a polished surface, you can then use it to focus the sun on tinder. Said tinder is then used to start a fire. Note to all hikers, take a lighter and a cell phone, too.