Firing someone is not an easy task and I don't envy managers and employers who have to do it. But some employees make it easier on management by crossing the line in such flagrant and unprofessional ways that their employers have no choice but to say "byeeeeee" (only in a more professional way, and with more words and paperwork).
Someone asked managers of Reddit: "What is the most unprofessional thing an employee has done that resulted in an immediate termination?"
1.) From SandmanD2:
I gave my secretary a document that I wanted incorporated into a letter I had written, and she hucked the document like a frisbee into her trashcan. It was literally my only copy so I had to walk over and fish it out. That was her last day.
2.) From SgtDefective2: