This occurs when the boss walks around to check cubicles, to see who is in attendance or what you doing at any point of the day when he or she is bored. This is to make sure that the employees know and remember who is in charge. It becomes a nuisance or annoyance to employees who are hip to the game.
I was planning on sneaking out early from work on Friday but I had to wait until the boss did his afternoon cell check to see who was still in the office or working.