"Clinic" play is a definite turn-on.
I can't think of a time in my life when my thoughts and desires didn't somehow involve being enema'd and rectally examined by an understanding, skilled and enthusiastic 'nurse'. I would especially enjoy being strapped onto an OB-GYN exam table equipped with knee crutches so that I'm in the most exposed and embarrassing position for my nurse while she administers a series of 'high' enemas - very warm and extra soapy to insure that my need to use the toilet is both strong and continuous throughout my treatments.
After my nurse has made sure that my entire colon has be quite thoroughly evacuated, the next hour would again be spent in the treatment table while she performs both a digital and speculum assisted examination of my anus and rectum, working slowly and patiently to "open me up" just as wide as I can comfortably go...and (of course) paying particular attention to massaging and milking my prostate. It would please and delight me have my nurse take complete control over every aspect of my bodily functions via the use of enemas (and maybe with urinary catheters?) for several hours each week. The only problem is that I've spent the better part of a life-time searching for the kind of 'nurse-companion' that I'm looking for!