1.Two liter bottle of chlorine (must contain sodium hypochlorate)
2.Small amount of sugar
3.Small amount of water
Mix all three of these in equal amounts to fill about 1/10 of the bottle. Screw on the lid and place in a mailbox. It's hard to believe that such a small explosion will literally rip the mailbox in half and send it 20 feet into the air! Be careful doing this, though, because if you are caught, it is not up to the person whose mailbox you blew up to press charges. It is up to the city.