Fire extinguishers are large metal cylinders used to put out unnecessarily flaming stuff. Though generally bright red, they can also appear in more attractive colors for decorative purposes. Among these are purple, neon green, pink, and the ever-popular rainbow polka dots.
Most fire extinguishers filled with some type of foam. Others, like those in many churches, are filled with holy water in case there is an outpouring of sin that creates Hellfire. And yet others are filled with nothing at all and are instead used to attempt (usually unsuccessfully) to suck up the fire. Most who use the empty extinguisher don't live to tell the tale.
One of the least known uses of fire extinguishers is in spaceships. In what is commonly called the "extinguishing method," a fire is lit under the rocket, normally by Boy Scouts. A very large fire extinguisher is then used to simultaneously put out the fire and force up the spaceship. This is becoming the most common mode of liftoff, as dealing with combustion is a tricky and complicated art that gives most people headaches.