when are you allowed to use your vehicle's horn?

Ah, the humble horn—Australia's vehicular megaphone of choice. You're generally allowed to use your horn to warn other drivers or pedestrians of your presence if there's an immediate danger, like someone stepping out obliviously or a car about to merge without looking. It's not your personal soundtrack for frustration during a traffic jam or to serenade your mates. Misuse can land you a fine, so keep it legal, folks. Essentially, the horn is for safety, not for symphony. Consult your local road rules for the precise do's and don'ts.