More people shoot themselves in the foot, get fired, or destroy promising careers by opening their big fat mouths than any other way. And that goes for communication of any kind: face-to-face, phone, email, text, you name it.

Executives and business leaders are especially adept at documenting stuff they shouldn't even be thinking, let alone doing. Don't ask me why, but it always seems to turn up in civil depositions, criminal investigations, and congressional hearings.

Here are recent examples:

In 2011, HP vice president Scott McClellan reportedly shared previously unreleased details of the company's cloud computing strategy on his public LinkedIn profile, tipping off competitors to confidential information that should have remained under wraps. McClellan, who had spent his entire 25-year career at HP, now works for Red Hat.

In the largest insider trading scandal in history, former McKinsey managing director Raj Gupta, AMD CEO Hector Ruiz, and IBM senior vice president Bob Moffat revealed confidential insider information to billionaire hedge-fund manager Raj Rajaratnam of Galleon. It didn't end well for any of them.

Granted, there's a broad spectrum of things you should never say at work, from pushing the limits of sexual harassment to risking an indictment for securities fraud. And these days, almost anything you say will offend someone by crossing some amorphous boundary of political correctness.

Nevertheless, if you like what you do for a living and don't want to end up pounding the pavement looking for a new line of work, here are nine things you should never, ever say at work. If you do, you're just asking for trouble.

"I probably shouldn't be telling you this, but ..." What follows is never good--and almost never legal. If you shouldn't be saying something, then don't.

"Do you really think we violate their intellectual property?" Unless it's in a documented attorney-client privileged communication, don't even think about saying anything like that.