Physical Danger
You're going to deal with some angry people. Even some crazy, angry people.
If you're working in customer service on the phone, you're safe. The customer doesn't know exactly where you work, and if they do, chances are you don't even give out your real name. (You don't, do you?)
However, if you're in customer service at an actual store where you have to deal with people face to face—you could be in some actual danger. Perhaps you want to check out the labor laws and look into hazard pay.