Excellent question!
(Regular normal middle-class white guy. Went out with some guys in college, but haven't had my hands down anybody's pants in a decade, too busy with career.) Fascinated with the gender-identity formation process, especially the myths relating to it, and working on a YouTube interview channel where I discuss with people how they understand their gender-journey. HIT ME UP, if this interests you!! I need audience & interview people.
I had some experiences of being put in a passive position in hospital / medical settings when a boy, and I guess when I think about them, the fun is in taking the ACTIVE role instead of the passive role. And yet, I don't stop thinking and wondering about and identifying with the younger guy who is being made to feel this or that. I go back and forth between savoring the ACTIVE role and the PASSIVE role. And yet, it's not a "linear relationship," between trauma and fetish at all -- of all the painful things I experienced, some things really work sexually, and some don't, and that's an interesting puzzle to analyze.
As a small kid, I had an injection in my ass-cheek that was very painful. I didn't know that it was better to relax, I was terrified, I clenched my muscles, especially my ass muscles as hard as I could, and my mom and a nurse had to hold me down. I was SUPER-SORE for days after. So, good strong, trauma, but I don't think about getting or giving injections. (Although some people on here do, which fascinates me!)
At 11, I went into the hospital for appendicitis, and a male nurse checked my infected appendix with a finger in the anus. This was painful, of course, and made worse by my mom watching and "sympathizing" with me. Being invaded by her female emotionality was worse than having my anus invaded!
Then, the next day when I was recovering, I heard another boy speak in hushed, amazed, and terrified tones about a third boy getting a rectal suppository before his operation: "They put a pill up his butt to make him go to sleep!" For some reason, that third one was what did it. The VISIBLE emotion in the boy's face is key. And of course, as I was laying their in the hospital bed, waiting for my stitches to heal, I couldn't help but think about what it was like to be the doctor doing it, the male nurse holding the boy down while he squirmed . . . or to be the boy who was getting the aneshetic suppository put up his butt.
It's the fact that the boy who told me the story WAS ALLOWED to have feelings about what he saw, that gets me. He was clearly terrified, weirded out, confused, needed to share, etc. There was nothing funny or erotic about it for HIM, though that perspective comes with hindsight. I was never allowed to have my own feelings or emotional processes when I was a boy; they always got shut down. Not the right time, made people uncomfortable, don't draw attention to yourself, etc. ALWAYS.
As a result of this Presbyterian anti-emotional bull-shit, I became a poet, and much of my career has been an effort to PROVE TO MY PARENTS that my emotions do matter, and that people will even pay for them. They were very Presbyterian, very shut-down-emotions type people.
So any time I see a scene in a film where a young guy gets his emotions shut off in a commanding way, this gets me excited and hard.
It's not a very nice fetish to have, and before I discuss in any more, let me say I have done A LOT OF WORK (one on one and groups) in order to take responsibility for feeling my feelings and expressing them appropriately . . . so I know my quirks and emotional processes very well, and doing to other people the kind of crap that was done to me, IS NOT GOING TO HAPPEN.
That said, I think it is useful for a group like this to analyze, at 53, what happened to me as a kid and how I've come to terms with it.
So, it's the shutting off of emotion . . . that idea that the doctor has the power to completely shut the boy down emotionally, to the extent of rendering him completely unconscious. THAT WAS DONE TO ME, usually in the form of my mother or father "pushing the off switch" as if my emotions were just a TV program they didn't want to watch.
It took many, many go-arounds in therapy before I was able to understand that the drama of the FEELING BOY being turned into the UNFEELING BOY was so interesting to me because it was MY DRAMA.
So that's the emotional part. Let me try to break down the attractiveness of the rectal temperature / anesthetic suppository scenario:
I) Slipperiness. OK, yeah, obviously you have the basic voluptuousness of something very smooth moving on your very sensitive membranes.
(People tend to go from there to prostate play, but that's a different thing.) Vaseline is key.
II) Violation of bodily integrity. It's like being killed; it's the LAST thing you would normally let someone do to you.
III) Dissolution of personality. There's very definitely a sense of one's identity melting away during penetration.... and sometimes that is just what a guy wants to feel. The male ego has to be, basically BALLED INTO A FIST in order to make things happen during the work-day. Any kind of anal touching activates the soft, relaxed, passive, feminine side of the male, that JUST WANTS TO BE PENETRATED It's so shameful, so female . . and that's what makes it exciting. A big macho football-player guy like Aaron Hernandez . . . but there are certain "feelings" he can only get when playing with another guy, and that just fascinates me!
IV) Emotional shut-down. As with hypnosis, there's that moment when the rectal anesthetic kicks in, and the younger guy's eyelids flutter and he falls asleep...that's SUPER-HOT!
V) Smallness and harmlessness of the act victim can't complain about it. This is the classic Howard Stern's mom point. "Oh Howard, you always make such a big fuss about everything!"
VI) Actual professional experience doing this. I worked taking care of Brain Injury patients, and had to give guys suppositories. It was great!
VII) Loss of power. This is hot. The doctor has his symbols of power, so that he can establish himself as the authority in the take-of-your-clothes scenario. For some reason it's even hotter if he's totally casual about using his power. "Alright, Kyle, I'm going to have you take down your underwear now. All the way down to your knees." Clothed male, Naked male . . . ALL THAT.
VIII) Squirming on belly. Any dude worth his salt is going to get a little squirmy when laying on his belly, and getting his butt worked on. OF course, the hard cock and frenulum are getting rubbed, which adds to the horniness which adds to the squirming. Hard to go wrong, with a guy on his belly getting his butt worked on.
IX) The imagination about the act. Anal stuff is more about the fear and imagination over being anally violated, than it is the sensations.
I really love the posters who could tell by the whether the jar of rectal thermometers was out on the exam table, or by the color of the thermometer, or by which nurse was coming to check them, that they were going to be getting a rectal temp, and that knowledge alone made them super-hard.
X) Theft. I find it VERY hot that some guy was giving guys rectal suppositories which knocked them out, and then he would steal all their stuff. Again, power, violation, etc.
XI) workguy has apparently left, but he had stories of being a macho working-class young teenage guy, with body hair and muscles and pride and all that, BUT, being in a socially inferior position as an orphanage kid, so that doctors and nurses in training would always be coming by to practice doing medical exams on him, and he wasn't allowed to say no. So workguy had all these great stories -- which REALLY WORKED FOR ME! -- about young doctors doing rectal temps on him, they had to hold him down and trick him into it, and he got VERY UPSET and VERY HARD; or a doctor wanted to practice doing an enema on him, and he didn't want it, but he couldn't say no, so the doctor gave him the enema, and he got VERY UPSET and VERY HARD. So it's the Red Passion -- the connection of anger and sexuality -- that really gets me. It's the combined situation of a young man with all kinds of masculine pride, being subjected to these procedures over and over again, and being RED HOT EMOTIONAL about it, together with the doctor who is totally cool and totally in control. That's what makes it work! He knows they're going to do stuff to him; he knows he's going to get VERY ANGRY and VERY HARD when they do it, so much so that he has to go run to his room and masturbate and cry right after; THEY KNOW, the staff at the orphanage and the doctors coming in, that he's the preferred subject for medical exam practice, that he always get VERY ANGRY and VERY HARD whenever he gets examined; they laugh at him before the exam; they trick him and manipulate him to cooperate; then comes the actual invasive moment, and, sure enough, he gets VERY ANGRY and VERY HARD; and, because he HAS to masturbate after the exams, there is a payoff for him, and a payoff for the doctor which keeps them both coming back. So it's very humiliating, and very exciting! OK, also actual hell. But very exciting to read about!
XI) Teasing. EVERYTHING down there is sensitive, so there's like A LOT OF WORK TO BE DONE before any actual penetration. Definitely go over with a wet-wipe, once, twice, maybe three times. Better, terry-cloth wash-rag soaked in nice warm water. Maybe ask him if he's ready, or nervous. Maybe have him do some deep breaths, or do some anal tighten/release exercises. Maybe accidentally swipe the thermometer across in a preliminary way, so that he feels the temperature change from the little breeze, or feels the little hairs stand up. Maybe "check" to see if he's ready with just a little touch of the tip to the ring of hair . .. then closer to the anus, where there isn't hair...then a little touch to the anus itself, kinda repeated here and there "in order to spread the vaseline around." I mean, you could make the warm-up last all day, if you wanted to. And of course you have to deny that's what you're doing. You can keep the thermometer in his butt for 10 minutes, and tell him he's imagining things when he says it's too long.
XII) You're looking for other signs of sexual arousal too. The change in breathing, in voice. The twitching of hands and feet. The squirming around on his belly. The hair on the back of his legs standing up. Looking for that rhythym of anal clenching and release. Start it up when it's slow, wait patiently when he's getting too fired up. People ruin it when they just go ahead and penetrate, with no warm-up. WAY TOO MANY botched medical exams vids. You want to TRAIN the guy that penetration-time = ejaculation-time. If he's not ready to ejaculate, you don't penetrate! If you train him that penetration = I've run out of erotic ideas, then you ruin it. Once the dude is TRAINED that the ego dissolution of anal penetration and the ego-dissolution of orgasm are going to be coming at him TOGETHER, when you think he's ready, then you'll have a happy puppy-boy on your hands!
XIII) Then there's the recruitment fantasy. I never had the proverbial "boy next door" to play with when I was younger. So some day, I'm pretty sure, If I'm super honest and super-clear about how the magic works, somebody is going to have their fuses all melted by what I write, and will write me back and say "Yessss......... that's exactly it, that's what I want done!"
1970's boy.
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I usually have a thermometer in my ass when I masturbate, and I've recently noticed how weird my fantasies are. In order to orgasm, I usually think about my mom taking my temperature, or, like I've been doing recently, being forced by my parents to kneel on the edge of the couch with a thermometer inside, and having a boyfriend walk in on me in that position and punish me further. These are both things that I wouldn't want to actually happen in real life, so why do I fantasize about them?