About a decade ago, Reddit pulled an April Fools prank at:

https://www.reddit.com/r/thebutton/

On that page was a button and a timer that counted down from 60 seconds and reset fairly often. It caused a lot of confusion and a schism in the community between people who pressed the button on those who didn't. If you pressed the button, you got a little colored circle next to your name in that subreddit. On the first day, a bunch of people got a purple circle with a 60 or 59 next to it. As it turned out, the timer reset any time someone pressed the button. You got a different color depending on the decade you pressed the button (60-51, 50-41, etc)

There was a lot of speculation and debate about what would happen as the button was allowed to count down. Dozens of religions formed to enshrine various beliefs and strategies for dealing with the mystery of the button. Many people wanted to let the timer run down as fast as possible, whereas others wanted to keep it going as long as possible. People made spreadsheets and dashboards and everything else to monitor the button and carry out their plans.

The button remained alive 3 months or so as people kept pressing it, and the timer finally ran down to zero, and the prank ended.