Nearly 98 percent of respondents said taking a colleague's food from the office refrigerator is unacceptable, making it the most-cited example of a breach of workplace etiquette.

The survey found that other behaviors that employees said crossed the workplace-etiquette line:

• Bad hygiene (96 percent)
• Bad habits (88 percent)
• Drinking on the job (86 percent)
• Wastefulness with paper (82 percent)
• Swearing (81 percent)
• Cooking smelly food in the office microwave (74 percent)
• Sneaking peaks at the BlackBerry® in meetings (64 percent)

"Some argue that in the 21st century, employers should move with the times and accept a more casual work environment," says Marc Cenedella, CEO and founder of TheLadders.com. "But employees beware, in every office there exists an invisible line between professional and unprofessional and it is very clear from our survey results that some common behaviors definitely cross the line."