https://www.youtube.com/watch?v=UJT8vfraCmk
When this was first presented, I was watching this in a large dark hall with this on the projector and the sound level set to extremely loud. Like a fool, I sat through this to the end wondering whether it was going to ever end rather than recognising it as a glorious troll.
My other idea was to get the line from dumb and dumber "Do you want to hear the most annoying sound in the world..." And just loop the sound continuously.
I might just try this project though and see how it goes.
The goal wasn’t to offend or clear out 100% of the customers - just make a large enough portion decide that outside might be more comfortable/conducive than inside. The 20 or so customers who were fine with the cacophony were easy enough to wrangle manually, and also generally either people we knew well .
Most Japanese know it as "the closing song"