get an empty coffee can and some candles. Chop up the candles and fill the coffee can up until it's about 1/3 to half full. take the can outside and make a small fire, then put the coffee can over the fire. when the wax starts to boil, pour some water onto it. Make sure you aren't near the fire when you do this, either by using a hose, or tieing a cup to the end of a stick, or something else. When the water hits the boiling wax, it will make a pretty decent sized fireball shoot up into the air.