Every work environment is different, with its own innate culture and written (or unwritten) rules. What's more, business etiquette – what is or is not appropriate in the workplace – can vary by industry, region or even country. While there are gray areas of what you should and shouldn't do in the office, some behaviors are just no-nos. Eating someone else's food from the common refrigerator or putting your personal calls on speakerphone are two examples. Below, we try to draw the line between what is acceptable and what will drive your coworkers crazy and potentially jeopardize your career.