If it's not true, it's defamation of character. Slander or libel, depending on if it was murmured around the water cooler or sent by email.
If it is true, it might be insubordination. You can get axed from most gigs by bad mouthing the person who can fire you. If you fail to use common sense, you can get spanked hard.
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-IronRaven
When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.