I do like bgpcf's idea of the itching powder. Not thought of that one before in this scenario. Add to that the wand or a vibrating butt plug both of which make him ache to move but in the knowledge that it will cause his cock some pain is a great predicament. I was wondering how we ( and that means you obviously ;) could get the choices up to three or more and he has to choose the best/worst of them. The tread mill, can the electro with a constant pulse on the cock be linked to the speed so he has to keep up or the power is increased? Sorry, it's easy to sit here and throw out ideas, I'm not the one doing the work.