The chances of my needing to ever use this technique are virtually zero, but the ingenuity demonstrated is worth it: Fire - Can of Coke and a Chocolate Bar.

This is a good example of overcoming functional fixedness, whereby people view objects as having only one use. In this case, the can of Coke is shown to be something other than a container for a beverage. It’s also a small parabolic mirror. The chocolate is more than a tasty snack: it’s also a mild abrasive.