To be fair, this will be a very tiny flamethrower. You would only be able to burn an elf or one of those things from Don't Be Afraid of the Dark. But it's still cool.
Sometimes something is so cool that you wonder why more people haven't told you about it. Then you realize that most of the people - at least the ones who both know about it and know you - think that you're going to use it to burn your house right down to the ground, and that's why you weren't told. So, to allow me to pass this information along to you lot of anonymous internet readers, let me preface this by saying, you need to be careful. Make sure the candle you use is small. Make sure the segment of orange peel is, too. Make sure the whole experiment is conducted on a substance that doesn't burn, near a big bucket of water.
Now light up that candle and place is somewhere steady. Peel an orange and savor its sweet, sweet insides. Then grab a section of peel and fold it very lightly in your hand, with the waxy outer side facing towards the candle. Be sure to hold it next to the candle flame, not above or directly below the candle flame. Now squeeze the orange peel so some of the juice squirts out towards the candles. You should see a sudden burst of flames as the liquid catches fire.
That liquid is part of the orange's defense system. It wants to attract big animals that will eat its seeds and 'redistribute' them away from the tree to take root. Mold and insects won't do this, but would like to snack on the sugar, so the orange has to keep its fruit safe. Running your hand along the skin of the orange, you should notice little pouches just beneath the skin. These pouches contain oils that kill insects. The oils are flammable, so when they burst forth, as they would if an insect breached the skin of the orange, and hit flame, they catch fire and make a fireball. This raises the question - when oranges finally gain sentience, will they weaponize their skin and come after us?
Via The Naked Scientists.