I worked at Staples when I was 19, and when I first started I was a "front end lead" (read: the only full-time cashier), so I would work behind the service counter at the front.
Once, I was standing up front while there were no customers when all of the sudden the voice of the general manager (we'll call him Bill) popped onto the phone's speaker, "Hey, Michael". I looked up and noticed the light next to "Manager's Office" was on. I instinctively replied, "Hey, Bill; what's up?", despite the fact that it nearly gave me a heart attack.
Bill proceeded to tell me to run something he needed to the back, which I did, and that was the end of that.
Then, one day I was helping a customer with some Cross pens behind the counter. I stood up to grab a key that was next to the register when I noticed out of the corner of my eye that the phone's "Manager's Office" intercom light was on. It made my heart jump because I hadn't talk to anybody through it, and I knew that Bill was in the back office. I immediately realized, 'oh my god, he's probably spying on me to see how my service is!'. It made me feel uncomfortable, until I realized it was an opportunity to be extraordinarily helpful and jovial with the customer and be "candidly" observed by my manager. So I did that. I rang the customer up and she left. The light went off after a few minutes of silence.
After that, I noticed the light come on a number of times on different days, which surprised me. I even ran to the back after helping a customer once, while the intercom light was still on, sneaked around the corner, and looked into his office window to see if it was really him. He was sitting there looking at his phone. I looked for just a moment when I heard from the speaker above, "<beep!> cashier to the front". I ran.
Bill was probably the greatest manager I've ever known, such a hard worker, a really cool guy to talk to, well respected by everyone, etc. In fact, if all managers were like him, Staples would probably still be a force to be reckoned with. So, it never bothered me the way it probably would have, had it been some creepy manager. This is necessary for the rest of the story, because had it not been the case, I would have probably called him out, etc.
Eventually I started being extra jovial all the time, because I never knew when I'd miss seeing the light come on and miss the opportunity to impress Bill.
Bill was so impressed with my service that I was given a raise and promoted to manager of the copy & print center about 6 months later, which eventually led to me opening my own print company and quitting Staples (after seeing how high the margins were), which led to me learning how to use Adobe Creative Suite and graphic design, which led to me shifting my focus to print design for clients (brochures, cards, etc.), which led to me meeting some guys who ran an Internet marketing company one day while trying to sell my print design services. They wanted to hire me full time, and did, so I began learning web design, then web development, then back end code, etc.
I always tell myself, 'I was probably destined for this kind of work', but the reality is that my entire life might have been changed by simply knowing I was being spied on by my Boss. I realize that it probably worked out for the better in my case, but the fact is, knowing that somebody is watching you causes you to change who you are. It's a form of control in and of itself. In fact, it doesn't even need to happen to you. Now that we have all seen that the government does spy on people, it's hard to imagine all the tiny ways that it might change your behavior and the things you say (e.g., online).