A long time ago, when I was in the military, I had surgery to my backside. So the prep for the surgery was a Fleet enema before going to the hospital (you haven't lived until you give yourself a Fleet enema in an army barracks). Once that was complete, I reported to the hospital.
At the admittance desk in the ward I was to stay, the lady manning the desk asked, in a relatively loud voice, if I had my enema. I responded to the positive, and then she showed me to the room. She tells me to strip down to my underwear, and stow my civvies in a locker, and then get into the bed. I do so, and a few minutes later an orderly and a nurse come by, and go over the surgical procedure with me. They tell me I must be completely nude for the procedure, so no underwear when I get on the gurney. A little later, a full complement of medical staff walk through the room, and brief me on what's to take place.
Then the gurney appears. One orderly asked me if I was in the uniform of the day. I reach under the cover, stripped off my briefs, and put them on a chair. I was then in uniform. They then move me from my bed, to the gurney, with the covers still on me. What I thought was awesome, was that everyone involved in moving me to the OR had not seen me buck naked, but they knew I had nothing on, and that I enema'd myself beforehand.
Once in the OR, I receive an epidural, and some anesthesia. I am not knocked out, and am fully aware of what's going on. I was moved to the table, and positioned for duty. I was in a very good mood due to the meds, and was joking around with the nurses and OR staff during the procedure. The surgery was successful, however, I never want to go through that again. Although the prep was fun!