It's mean to get someone fired from their job.
Dean was a customer waiting in a long line at the grocery store.
Dean wanted to tell the manager how the clerk was doing.
Dean told the manager that the clerk was working very hard at their job.
Dean told the manager that the clerk was way too slow and that he was never going to shop there again.
The manager gave the clerk a raise and more time off after talking to Dean.
The manager fired the clerk right after he talked to Dean.