What about one goes to a spa center to get rid of stress and stuff, to relax for a couple of days, maybe a week. At the beginning everything is quite usual: fancy robe, cozy room, comfortable massage table. The masseur helps to take the robe away and the person lays down with just a towel covering the naked bottom. Massage is superb and when the person is totally relaxed and pliant he feels fingers spreading his butt cheeks. Without a word the masseur pushes a slippery finger right in the hole to lube everything up. After a finger comes a rectal thermometer. Any questions and protests are shushed, because everything is done for the client's good.
After taking a rectal temperature masseur helps the client up and leads the totally naked person down the corridor paying no attention to the embarrassment and humiliation of the client. Through small windows in the doors along the way one can see several doctor's offices. In some of them there are other naked men and women and doctors and nurses performing invasive medical manipulations in plain sight. Again nobody cares if any patient’s body part is seen by others.
The person is led to a free office, where a cute nurse is already waiting with a bulging enema bag and a long nozzle. The first enema is nothing near pleasant, soapy and big. But again all protests fall on deaf ears. What's more the nurse explains that the documents the client signed booking this small vacation make the client their patient and until the doctor says he's free to leave the patient must endure all procedures or he would be tied to the bed by securities - huge strong men who would then follow every procedure and witness every step of the healing process no matter how invasive and humiliating.
The patient has to agree to several cleansing enemas and a shower. A strict doctor comes after and conducts an extremely thorough medical exam. He pokes every orifice, checks heart and lungs, gag reflex, muscle tone and sexual endurance. After that the doctor prescribes treatment and daily monitoring.
So for a week or so the patient endures daily enemas, rectal temps, maybe waxing/shaving of everything below eyebrows, milking for men, naked yoga and sensual massage, healthy diet, relaxing meditations…
On the last day the thorough exam happens again. And the doctor prescribes the patient to come back in half a year.
Next time the patient already knows he would be naked the entire time, undergo different pleasant and not treatment whether he wants it or not. Otherwise strong bullies make him do that and that would be even more humiliating…