I've got a play date with an old friend coming up this week. I'm in the dom role and I'd like to do something that prevents him from getting an erection (until I say he can, of course). I've been looking at all the cock/ball devices and I really don't know where to begin. How effective are they are preventing an erection? I don't want to start with metal because of the safety concerns and I'm trying to do this on the cheap. Should I just wrap his cock up with pvc tape? How safe is that? Are the cock straps with the buckles good for these things? Help!