I first encountered rectal suppositories when I was about 3 y.o. (I think even a little younger) and had pancreatitis (acute inflammation of the pancreas). Doctors prescribed me a bunch of medications, one of which was rectal suppositories that had to be inserted twice a day – morning and evening before bed. My mother inserted the suppositories, while I was lying in my bed in a diaper position. And it was a real nightmare.
The most interesting thing is that I was so little that I didn't even understand what was happening. I didn't know that a suppository was a "magic bullet" made of a mixture of oils and fats that my mother inserted into my bottom, that she did it with her finger, and that the suppository stayed inside until it melted and was absorbed by the rectum.
All I knew was that as soon as my mother said the words - "Honey, let's give you a suppository!" - my legs would lift up, so I couldn't see anything in the room except my knees. And immediately afterward, I only felt that terrible sensation in my bottom. I don't even know how to describe it - some kind of instantaneous mixture of pain, burning, the urge to poop, and a distension inside my rectum - as if something were forcibly expanding my poor bottom from the inside and it was about to explode.
This went on for several days, and during that time, I even developed a conditioned reflex. As soon as I heard those dreadful words from my mother again, I would start crying at the top of my lungs, without even waiting for my legs to block my vision and that dreadful feeling to begin to build in my butt. The word "suppository" itself became a real trigger for me.
But fortunately, I soon recovered and was never tormented by rectal suppositories again. They're actually quite common in our country, and many mothers regularly use them to treat their children for a variety of ailments up until they're 7-9 y.o., but (fortunately!) I've never had to deal with this again.
The next time I had to resort to suppositories was when I was almost an adult (16 y.o.), and of course, everything was different.