... because I used to be a copywriter and I know how difficult it is. And the copywriting on Australian public signs is nothing short of brilliant.

What makes it distinctive to a person used to the circumlocution and indirect language of English signs - which are aiming to be polite - is that there's an energetic directness of phrasing combined with a kind of 'don't blame me, mate, it was your mistake' shrug. Signs threaten you from all directions, usually with fines - but they don't tell you you're liable to a fine, they tell you that you'll get fined. Rather than giving you the neutral information that you might want to think about, they say flat out that if you do something stupid, then it's your own lookout. Really, the icon for 'public service announcement' in Sydney ought to be a down-to-earth little stickman pointing and laughing. Two particularly good examples:

1. On ferries, trains and other places worried about terrorism:

If you see something, say something.

It goes on to say report suspicious packages or persons, but in terms of being both general and common-sensical, it's terrific.

2. My absolute favourite, posted on the walkway above the crocodile enclosure in the Sydney aquarium (best place in the world, go there, go go go), and pretty self explanatory:

Do not enter.
If the fall does not kill you, the crocodile will.

Genius.

Anyone else have favourite signs or slogans?