You probably know that posting derogatory comments about your company or teammates on social media can get you fired. But under the terms of at-will employment, even a small oversight such as failing to keep your boss in the loop can result in an unplanned trip to the unemployment line. For example, did you know that Apple CEO Tim Cook fired an executive for changing the schedules of Apple Store employees and “not fitting in with the company’s culture”? With that as a backdrop, here are six surprisingly common mistakes that can get you fired:

Thinking Too Far Outside the Box

Software engineers and business analysts are supposed to be innovative problem-solvers, right? Actually, it depends. Peppering your boss with disruptive or far-out ideas can lead to dismissal. “Know your boundaries,” advised Samantha Hurwitz, author and chief encouragement officer for Flipskills, a leadership-coaching firm based in Toronto. “Don’t suggest ideas that are too creative or risky if your boss is looking for incremental change… Otherwise, he may think that you don’t understand the organization’s goals or that you’re too much of a risk-taker.” Lesson: Think outside the box—but stay aware of the box’s edges.

Throwing Your Teammates Under the Bus

Your pet project came in way over budget but it wasn’t your fault. Your instinct for self-preservation kicks in as you rush into your boss’s office and demand that he release the programmers who can’t write tight, error-free code. To your surprise, he gives you the axe instead. Lesson: Never point fingers. Briefly outline the issues without laying blame or naming names, before quickly switching gears to offer solutions. As Henry Ford advised: "Don't find fault, find a remedy."

Lack of 'Offensive' Communication

You think you’re a rock star because you spend 10 hours a day in your cubicle crunching code. Unfortunately, the director has no idea what you’re up to, and when the department’s budget is slashed, you’re the first one to go. Lesson: “Don’t make your boss come to you,” Samantha Hurwitz said. “Take the initiative to volunteer information. Make sure everyone up the ladder is aware of your activities and accomplishments.”

Playing Devil’s Advocate

You tend to view your boss’s ideas with a critical eye and you’re quick to point out why his or her solutions won’t work. “Over time, your boss won’t want you around because he’ll come to view you as a blocker of change,” said Marc Hurwitz, author and chief insight officer of Flipskills. Lesson: Leaders claim they like “having a devil’s advocate on the team,” Hurwitz added, “but research shows that they prefer supportive people who try to make their ideas work.”

Trust Violations

Network admins and security pros are well aware that leaking juicy tidbits of information gleaned from company emails can lead to termination. But what if you accidentally open a confidential executive memo or folder that you’re not authorized to view? Should you keep your mouth shut or come clean? “Even if it’s an innocent mistake, you should tell your boss about it,” said Nicole Williams, CEO and founder of WORKS, a career-coaching firm based in New York City. “If the information in that memo gets out or your mistake is uncovered during an audit, you could be fired.” Lesson: As the saying goes: It's not the crime, it's the cover-up that gets you.

Getting Too Chummy With Customers

So you’ve bonded with a few key stakeholders; sometimes you even talk business over lunch or drinks. Your close association leads to informal email exchanges, text messages and the sharing of inside jokes. But you might get the boot if a co-worker sees your messages and files a complaint. Lesson: Engaging in casual communications that are overheard or viewed by others can be problematic. You never know who could be lurking around the corner, so always maintain a professional demeanor when you interact with clients, teammates or managers. And never send emails or text messages during Happy Hour.