I've been putting medical instruments into the wrong holes again- my stretched peehole is big enough that a metal anoscope goes in with no trouble at all and lets us take a close look at my bladder sphincter! I use a borescope (wrapped in cling film to protect it from piss, since it isn't waterproof) to give an endoscopic look at the opening to my bladder, and then go ahead and pee. This video includes views from the outside, so that you have context for what's going on and can see the piss trickling out, as well as the extreme close-up endoscope views.