'You're wrong'
"Openly criticizing or pointing out your boss's mistake is a sure way to be excluded from future meetings or ignored the next time you raise your hand to speak," says Rosalinda Oropeza Randall, an etiquette and civility expert and author of "Don't Burp in the Boardroom."
If you feel your boss has made an error, there are better ways of addressing this, she explains.
You might say, "I may be misinformed on this one, but I was under the impression that ..." This prompts them to reconsider and correct the information if necessary without putting up their defenses. "Whatever phrase you use, say it with a helpful and cordial tone," Randall says.