I had a kitty YEARS ago named Trouble, he was the only cat I ever owned that was trained to do things. I could get him to jump from the floor to my shoulders, he ALWAYS got in the tub with me when I would soak, and would ask my permission to get on my lap. He seemed extra sensitive to whistling! If I would wistle, he would come running, if I kept it up, he would jump up on me and nip my lips as if telling me to please stop. I haven't thought of him for a long time. And you just brought back very fond memories of a wonderful boy.