Oh my goodness, what do you think you are doing? This is a library! You can't have yourself exposed like that, in my library! You need to be punished for this and the only thing that would be fair is for you to stroke your dick to my every instruction. Yes, that'll do. Keep stroking as I tell you how fast and what hand to use. Eventually I get myself awfully worked up instructing you that I start playing with myself and count us both down to orgasm.