This guy recently started at my office and he seems to have singled me out for a certain kind of attention. I smiled at him on his first day to be friendly/welcoming, but since then he's started staring and leering at me a lot. If I end up alone with him in the kitchen he'll very obviously look me up and down and give me "bedroom eyes", and when he passes my desk on the way to the bathroom, he'll deliberately turn around and leer or wink straight at me. There's no way I'm imagining it, it's happened too many times. He's never spoken to me before, and he only does it when it's just him and me around, which makes me think he's doing it to make me uncomfortable, and that he finds my discomfort funny. I don't feel like I can go to HR either, since he's never actually said anything to me and I can't "prove" it. Has anyone ever had a situation like this?