My boss is technically my coworker.
I screamed my lungs out after it became clear that he didn't give a shit about employees that bring him money. After snatching all funds from a finished project on time, failing to deliver on the promise about bonuses (it's what I used to motivate employees to deliver the project on time), refusing to buy a new chair to replace the one held together by scotch tape and careful balancing, I decided to quit with maximum damage.

I screamed so that everybody would hear it. That encouraged another guy to get in with quitting, and within 1 month most of the team had quit, leaving the boss with a risk of lawsuits for prepaid contacts not delivered.

Knowing that piece of shit, he probably recovered and is treating other people badly, but at least every single person from the team experienced the biggest jump in careers straight after that.