A friend of mine works AV at shows that have rotating DJs and one of the things she has on her mixer board is "The Suck Button."
It causes a mic at the other end of the room to get cut into the DJ's live feed monitor with a semitone shift down and some reverb. This causes all sorts of inner-ear chaos and usually clears a DJ off the stage when they're over time within a few minutes at most -- usually under 30 seconds. One time they were trying to figure out why it wasn't working and discovered that the DJ had muted their monitor feed, which explained why they were not only peaking the meters but over time: They hadn't heard the FOUR warnings from the back of house that it was time to wrap up.
There was a coffee shop ages ago in SF that would every few hours play a cacophony (e.g. multiple songs at once). I assume it was to drive away people camping on their laptops to rotate tables. Understand but super annoying to people like me who had a timer to but food or drink no less than hourly to be a good citizen
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.
That's extremely annoying. I have a Bluetooth speaker that I was intending to repurpose into a device to combat inconsiderate smart phone usage. I connected it to my laptop and started playing multiple streams of Punjabi MC - Beware of the Boys. It was torturous.
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.
We had a friend who would play Metal when the ice cream store he worked at was closed but the customers were lingering too long. It generally worked, as he was immune.
In Japan it's pretty much an institution that shops play an instrumental version of Hotaru no Hikari (which is basically Auld Lang Syne with different lyrics) when they're closing.
I introduced my local restaurant owner to Mongolian Techno and the late night bar flies and some of the kitchen staff have never forgiven me. He won't admit if he plays it for himself, or because of them :)
It's 3am and we're arguing some insipid minutae over technically illegal tequila shots while one drunk girl is breaking it down on the tiny dance floor :)
We did this where I bartended as well. Generally 15-20 minutes after serving the last drink of the night.
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 .
I was at a coffee shop once that was playing metal while my writing group was meeting there and I just thought they had excellent taste (it was not near closing time)
That reminds me of the "speech jammer", which won an Ignobel Prize last decade. It's an acoustic gun that combines a directional microphone and speaker array with a delay, tripping up the speaker.
It causes a mic at the other end of the room to get cut into the DJ's live feed monitor with a semitone shift down and some reverb. This causes all sorts of inner-ear chaos and usually clears a DJ off the stage when they're over time within a few minutes at most -- usually under 30 seconds. One time they were trying to figure out why it wasn't working and discovered that the DJ had muted their monitor feed, which explained why they were not only peaking the meters but over time: They hadn't heard the FOUR warnings from the back of house that it was time to wrap up.