Calling someone's workplace and leaving a message that implies that they do no work is slander. Should you actually cause that someone to lose their job, you can be sued for slander. That doesn't scare you? Well, think of it this way: If someone is 40, and you cause them to lose a job paying a measly $25k a year that they may have stayed at until retirement at 65, that is a base (25k x 15 years) actual damages suit of $1,125,000. It'll probably be more, assuming the plaintiff's lawyer isn't sleeping through the case, and assuming the judge will also slap you with a nice punitive damage award as well.
Don't have a million bucks sitting around? Don't worry, the court can force you to liquidate most of your assets to pay; including your house, your business, your car, etc.
Maybe you should think about that before acting like a psycho.