@Smoothnylon143, Even if you were able to dilate your urethra enough to take the smallest tampon you would be setting yourself up for terrible disappointment and pain. First off, your urethra isn't designed to handle a tampon of that size. So let's see what other things we can say.
1. The lining of the urethra is very sensitive to something as rough as a tampon.
2. Tampons are designed to soak up fluid and when that happens it expands, so that is going to dilate even more. So what is the design limit of the urethra, and then removing it. I think we just hit the red zone of pain and discomfort...
3. Now do we want to discuss the fact this may cause a Urinary Tract Infection, they can be quite nasty...
4. Now let's ramp this up a bit, as rough as a tampon is and the urethra is not the same as a vagina which can handle more, you run the risk as woman are taught, Toxic Shock Syndrome. Micro lacerations to the lining of the urethra creates a breeding ground for some nasty stuff that can kill you if not detected and treated in time.
Keep it as a fantasy mate, and stay alive and well!