I shouldn't have dreaded the first time my pediatrician did it in the 1960's, because my mom fully inserted her finger at every enema.
But there was something very different about being required to bend over a table while nude and having a man I had great disdain for spreading my butt crack and inspecting my anus. Then putting on a finger cot and lubing my anus before he lubed his finger and pushing it all the way in.
The exam seemed to last forever and my mom always told me hold still so the doctor could finish the exam. The doctor twisted his finger around and pushed on my prostate too.
He talked to my mom about the shape and size of my prostate while my erect penis throbbed and bobbed up and down.
He never wiped the lube off or gave me a tissue to do it, so my tight-whitey's were always covered with lube from my butt crack.
I really dreaded it the second time because I knew what was going to happen and he asked his nurse to stay and hold my shoulders down so he could get the exam done easier.
After that I relaxed and enjoyed the insertions much more.