The ultimate kind of doing graffiti is to use a fire extinguisher as writing tool. All you need is a refillable device. Unscrew gas cartridge and replace fire extinguishing agents with colour. Then, after reinserting gas cartridge, the fun can begin. Obviously there is only a short time to write with a fire extinguisher; you can play as long as propellant is available only. So it is used for tags mostly, but for large tags!