The signs used to be made up of little individual letter stickers, and you could pull them off or rearrange them as you pleased. In the sentence
At night, rave near the guard's compartment naked with a blue light, for example, you would have to strip off half of the
m to make an
n.
Sometimes you see the carriage numbers reversed in this way, so there's no way to tell which one you are actually on, which isn't a big deal unless you're having to call a cleanup crew or a rescue team (CityRail trains have a tendency to derail. Some, like the Millenium Train, don't even fit through some station platforms). It was perhaps five or six years ago that someone had the bright idea to alter the guard's compartment sign. Within a few months, every single train in Sydney's CityRail network had been thusly disfigured. Immeasurably amusing for your average high school commuter, let me assure you.
Until, gasp, tragedy struck.
Some wise guy decided to replace all the sticker stencil signs with large printed images last year. No more raving naked. Ever.