I once met someone with a white pet rat on a train and the rat was constantly climbing all over her, even running up her sleeves. She said she couldn't live without it and loved it to bits. I don't know what kind of rat it was, but I'd bet it wasn't rattus norvegicus. :) It was a gorgeous animal.
An actual rodent rat, sitting washing itself on his shoulder, or more accurately his back, right behind his head.