Broke Ass Stuart had a lot of stuff for this. Also Craigslist has (or had) a whole section of free events. I never had problems finding free entertainment for the 10 years I lived in SF.
Check your library for local events, and local museums for resident free days.
Go to every park.
Go to every gallery.
Go to every neighborhood you've never been to and be curious about it.
They don't perform these acts because they hate anybody. It's theater. But Donald Trump will never accept that as long as he is one of the caricatures on stage. His ego is too fragile.
My area has a playground built to accommodate disabled children and the adjacent property is a gun range. There are also soccer fields. Imagine children going down the slide and swinging and kicking the ball around all to the sound of not-so-distant gunfire. The 200 meter range even shoots towards the soccer fields.
One big problem with GitHub that is only briefly touched on in the article is that developer teams used to be able to use the feed to get useful updates on what their team was working on. Now, it's polluted with unrelated AI generated suggestions. So for those of us who use Github as an enterprise application, we previously had a user friendly app that helped us get work done, but we now have a user hostile app that participates in the attention economy, luring us with distractions, which are the opposite of what we should be doing at work. The GitHub feed is now anti-focus, anti-work, algorithmic buzz, and enterprises like my employer still pay for that.
Run strace (or falco) and log every file open. When you hear the sound, reference the log of what files were accessed at that time.
Run tcpdump and capture all traffic. Analyze it in wireshark, searching for a time window around when the sounds happened.
FWIW putting pranks like this in cron or systemd is a common way to haze people who have bad security practices. We also used to set the default run level to 3 or 6, but of course that doesn't make sense in the era of systemd.
Freaking awesome start! I will revisit this when it gets to laser printing.