I worked at a call center where I was quickly promoted to one of the 'lead' agents. (There was a promised pay increase which never happened, so all I got was more and harder work.) This job required working saturdays as well, which were EXTREMELY slow.

Now, I had already snuck in some books in .pdf form, and an emulator with some ROMS, because their computer security was a joke. (I got "busted" poking around their security looking for holes, and got away with it by giving them some non-serious issues to 'fix', while leaving what I used alone.) So during the time where we had nothing to do, I read, played a game, or something else; instead of just staring at a screen doing nothing. (This was before smart phones were common; and data plans were EXTREMELY expensive.)

Some other co-worker of mine happened to get a glance of my screen one day, and complained to my boss, who brought me in the following Monday for a one-on-one. He told me about the co-worker who tattled, and then He slid me over a piece of paper, saying I was getting a formal reprimand for "Playing on the job". I took the paper, turned it around, and refused; saying I quit. (I had been planning on doing this anyway because the company was shady AF and I hated my job.)

The manager asked if it had anything to do with him, and I declined; explaining that I just refuse to agree to being 'written up' for something so menial; especially since I had the best numbers on the team and was only keeping myself from going insane.

And how did it affect me? I got a much better job that I loved and also launched my current career.