Another one: they're in uniform, carrying a clipboard or other gear, and checking merchandise on the shelves, but, no, they don't actually work there, either. They're on the job, yes, but they're just a delivery person, or some other third party checking inventory in some capacity!
Ugh, I've been that guy too many times. I often do inventory at the bar where I work, which requires me to actually step behind the bar. So people come up and try to order things from me because I'm behind the bar, and I just want to wear a big sign that says, "I'm not really here! Don't look at me!"