I think most people notice; particularly if there is an exceptionally large penis swinging around. I have never, ever heard anybody say 'nice cock' to a stranger. That's 12 years of football and 10 years at a local gym. In fact, I saw a man get punched out playing billiards at a bar because he said "you're turn, pumpkin" to his opponent. I wonder what that guy would have done if somebody made a remark about his cock in the bathroom?? In my experience, I would highly encourage people to keep cock remarks to themselves unless its somebody they know. I have noticed that the more well endowed tend to parade around in the locker rooms without thier towels more often than those of more modest endowment.