Sounding

I would totally love to do this, but the potential for infection is high, even with sterile equipment. And the technique good to not damage the urethra. The urethra is difficult to repair. (Worked in related field)

But a nurse doing it sterile and with good technique... damn hot.

And did you know Hegar dilators are normally used to dilate the two corpora vessels on either side of a penis to be able to insert a prothesis. The corpora are definitely larger than the urethra.