I went to an auto supply store, and bought 2-foot (60cm) lengths of clear flexible plastic tubing in the following outside diameters: 1/8-inch, 3/16-inch; 1/4-inch (approx 6mm), 5/16-inch, 3/8-inch, and 1/2-inch (approx 12.5mm). The 1/4-inch tubing is very similar to the plastic tubing used to pump air into aquariums.
I rounded and polished the ends, sterilized them, sterilized my hands and the end of my penis, and started playing.
I didn’t even bother with the 1/8-inch tubing, starting right out with 3/16-inch. It went in nicely, although it could have been a bit more flexible. It took a little while to push it through my prostate and urinary sphincters. What a remarkable feeling it is to have your prostate area invaded like that!
This was such an outlandish experiment for me that I was literally shaking. I was shivering as if it was cold in the room, but it was plenty warm.
I pulled it out, and went to the 1/4-inch. That went all the way in easily. I noticed that once it was in my bladder, I had a kind of shuddering effect. The pee would flow through the opening, then the tube would be pressed against the wall of my bladder, shutting off the flow. Then with the pressure off, the tube would float away, and once again pee would flow. This shuddering against the soft bladder wall happened at a rate I’d guess to be around 4 – 6 cycles per second.
Next came the 5/16 tubing. It was a big challenge getting it all the way into my bladder, but I managed it!
The 3/8 could only be put in about 7 inches, to about where my penis disappears into my body. It just would not go any further, and I wasn’t willing to risk injury.
All in all, the afternoon was tremendous fun. However, a few weeks later, playing with inflating my bladder with water, I gave myself a huge infection. I recovered after a week, but have decided none of that is worth the risk. I have found much better ways to have sexual pleasure and orgasms, such as described here: Advanced Male Masturbation