Spy on my friend see his penis watch him sleep makes me horny?

I have a friend that is straight. He knows that I like him, he knows that I like to look at him, he takes great lengths to make sure I do not see him, however I just can't help it, I find myself looking at him, trying to get a glimpse of his penis through his pants, especially when he is wearing his pajama pants, he does not change in front of me for obvious reasons, he just doesn't want me to see him like that because he knows i'm going to jack off to the image of him in my mind. He has ca ought me in my room masturbating (we are roommates) and he just turns and walks out with out a word. So i guess my question is what can I do to get him to at least let me see him or even part of him? If he would just show me his penis I would be happy forever. I mean he knows I like him in that manner, he even tells me how big he is, but refuses to show me. Every so often we will get into a sex talk, but never about him. I really need an answer soon, he is out now with friends and we will be home alone tomorrow, I will use any thing that is offered...please give me some real answers...just calling me names doesn't help