"Why would someone like you have never had sex before?"
While in the hospital for appendicitis, I needed an ultrasound to determine it wasn't something wrong with my fallopian tubes. I told every doctor and nurse that worked with me that I was a lesbian and had never had sex (knowing that it would help with them on issues of pregnancy and other questions) but when I got to the ultrasound room, the nurse working there didn't believe me.
I explained that I was ace, and never had PIV, and she looked me over and said "Why would someone like you have never had sex before?" The reason this was important is because there's two ways to conduct an ultrasound: over the skin, or through the uterus (penetratively).
The nurse was confused mostly because I was 20 years old and had never had penetrative sex, and also made notes about my body being "very sexual." Which overall is very uncomfortable and not what I asked for.
So she spends a good five or so minutes, which feels like ages with my lower right quadrant burning and feeling like knives are being skewered into me, trying to figure out if I'm "lying." And then gets upset when it's clear I'm not lying, since she told me to use the bathroom earlier (apparently over the skin/stomach ultrasounds need you to have a full bladder).
Compound this with my being trans and generally not wanting to be there and everyone misgendering me (I was too scared to tell anyone at that point, medical malpractice is all but intentional when it comes to us trans folx) and I can tell you it was not a fun experience.
The good news was that, while I did have appendicitis, it was minor enough that all they had to do was starve me for 30 hours and the inflammation went away! The cost was somewhere around $20,000 before insurance.