My first experience with catheters goes back around 25 years.
I'd been to see a play doctor (Doc Colin) who I'd been chatting with on the now defunct yahoo groups. After a general examination he told me that he'd found that I appeared to have some urine retention and needed to "pop a little drainage tube" into my bladder. I remember that phrase as clearly as if it was yesterday.
At that point I had never heard of this procedure but agreed to let him do this. Needless to say I was nervous but equally excited about having an invasive medical procedure performed on me.
Doc Colin explained what this involved and the sensations that I would experience, although nervous, I was looking forward to having this done.
He began by "painting" my now erect penis with a red coloured liquid, which I now know to be Betadine, and left me for a minute or two to let it dry and then returned with a catheter and bag and a couple of syringes. The first syringe was a lubricant which he injected into my urethra and worked it down with his fingers and then opened the catheter package and smeared some of the lubricant on the end of the catheter. He then told me that he was going to insert the catheter and told me that it may be slightly uncomfortable but if I felt any pain to tell him and he would abort.
I did feel some discomfort as the catheter passed my prostate and as it entered my bladder and he then took the second syringe, attached it to the catheter and began to press the plunger on the syringe telling me that he was inflating a balloon inside my bladder to keep it in place and to tell him if I felt any pain as he was doing it, which I didn't. He then gave a couple of tugs on the catheter which felt as though I was being wanked from the inside and connected the catheter to the bag. Although I didn't feel as if I was peeing I could see the bag beginning to fill with the yellow stuff and if I remember correctly there was 200 mls in the bag.
He then began auscultating my lower abdomen above the bladder area whilst also tapping and pressing the area and after a few minutes could see the bag contained around 350 mls. He then told me that I was completely empty and was going to remove the catheter and then deflated the balloon and gently pulled on the catheter to remove it, which was the most uncomfortable part of the procedure.
Over the next 2 or 3 years I visited him for examinations around half a dozen times and always looked forward to having my bladder drained.
Fast forward around 10 years:
Although I was still in "patient" mode I began taking the doctor role and have since met with many guys who were medical fetishists and have introduced them to the pleasure of catheterisation / bladder control and saline bladder "washouts" while still using Doc Colin's phrase "I need to pop a little drainage tube into your bladder". I have some videos of me catheterising guys and also self cathing on xtube, same user name there.