No, not the Yugoslavian entry in the 1974 Eurovision Song Contest. It's the sound we want from our Bay lights on warning, if fitted (or added if not). The stock US-style electromechanical buzzer sounds awful, and warning "relays" fitted to earlier Golfs and like (which are still around on eBay) just sound like a badly-programmed Sinclair ZX81. We want a nice, sonorous "Bong!", as on modern VWs. Unfortunately, bonging duties are performed by a tone generator built into the dash, so not an option. Enter the BMW Auxiliary Bonging Unit, built into the footwell of various Bimmers from a decade or two ago, to support - I believe - various options like reversing sensors. BMW part number 8360995. There seem to be various versions, but the one with the green base gives you the range of pinging and bonging, to use as you wish. Also seem to sound better. Loads on eBay for a tenner or less. All tones apart from T5 are triggered by taking the appropriate contact pin low (to earth). T2's the easiest for triggering from a low-going door switch. It's quite pleasant, and runs continuously. T5's actually mellower, but needs to be triggered by a positive level on the pin, so some transistor-age necessary to flip the door switch signal upside down. If you've got a modern ignition switch with stuff like key-in-switch outputs, with a few trannies an a bit of diode logic, you could have a whole warning symphony going. I was lucky enough to get the original connectors with mine, but easy to solder leads on. Needs an unswitched +12 supply, but only consumes about 0.5mA when it's idle. Be warned: these are bigger than you think, as they've actually got a real loudspeaker in, rather than a piezo transducer. Compare with the "relay" in the background. Here's a Japanese fellow demonstrating what's available.