Adelaide Metro is the public transport system serving Adelaide, South Australia, where passengers tap a smart card on a validator when boarding buses and trains to pay their fare. The tap-on beep has become a small everyday marker of that routine, recognised by locals from daily commuting and shared online by creators who want an authentic local detail. Because the sound is so brief and specific, it is often reused in travel videos, social clips and edits about city life, where a single beep can place the viewer in Adelaide without any explanation.