Mine always was on my birthday or the next business day if my birthday was on a weekend or holiday (US Labor Day). So going to see the pediatrician was never a surprise.
When I was just a week or two from turning seventeen, and school was starting in just a few days, my mom said one morning, "Don't forget we're going to the new doctor today." My fourteen-year-old brother said, "Okay," because we'd known for weeks that he needed his sports physical for his first year at the high school. I didn't respond, because I didn't play sports, and my usual visit to the pediatrician would be on my birthday. She turned to me and said, "you too." I said, "But aren't we going to [my pediatrician's name] on my birthday?" She said that my brother and I were grown up enough now that we didn't need the pediatrician anymore (I was a late bloomer, hence my having to go there through the age of sixteen), so she was taking us both to this new family practitioner.
In the car on the way there, she asked if we had undressed in front of each other since we had gotten our own separate bedrooms four years earlier. We hadn't. Since she had seen us both naked at our exams with the pediatrician each year during that time, she said that we'd be seeing that each other had changed a lot since then. My brother asked if she had to be in the exam room with us, and she said they had a policy of either a parent or a chaperone from staff, so she had told them she'd sit in. Again, my brother just said, "Okay," basically willing to go along with whatever was required for him to play sports.
I, on the other hand, was nervous. I was used to my mom being at all my exams, but this would be a new doctor, as well as my athletic younger brother who would tease me for being a nerdy indoors kid. Despite finally having "caught up" puberty-wise the prior year, I was not then (and am not now) either a grower nor a shower, and I thought the same might not be the case for him, leading to even more teasing. Add on to that the fact that during my sixteen year old exam, for the first time ever, I got an erection during the genital exam, and I was more nervous than I'd ever been before for a doctor visit.
When we got to the doctor's office, the lady at the desk gave my mom one clipboard for my brother and me another clipboard for myself. I never got the clipboard myself at my pediatrician, so that was new. After filling out the forms and waiting, a nurse came to the waiting room door and called my name. My mom, confused, walked up to the door with me and started talking with the nurse. I couldn't hear what they were saying, but finally my mom said, "fine," rather loudly, and then something else I couldn't hear, and sat back down next to my brother. The nurse took me back to the exam room, and surprised me by not telling me to get undressed. She had me take off my shoes to get on the scale there in the exam room (at the pediatrician, it was down the hall), and she proceeded to do the usual temperature, pulse, and blood pressure measurements the nurse at the pediatrician would do, as well as HEENT stuff I had been used to my pediatrician himself doing. She then left the room and told me the doctor would be in soon, and all I had left was the hearing test. She left the door open, so I could later see my brother walking by in just a hospital gown with the same nurse, and my mother behind them. The doctor soon came in, closing the door behind him, and his examination of me was super quick. He used the stethescope over my shirt even, and I was only sitting on the exam table, never lying down. After probably barely a minute, he asked me to hop off the table lower my shorts and underwear, then did a very quick hernia exam, and that was it. He asked if there was anything else I needed before he took me back to the waiting room, and I said the nurse had said I would get a hearing test. He looked confused but said he'd send her back in. She came back in and said, "you wanted a hearing test?" And I said I thought she said that was the last part of the exam, and she laughed and said, no, she had said hernia test, and that's what the doctor came in for. But she had a little handheld tone generator and asked me if I could hear the high pitched tone in each ear, which I could, so she walked me back out to the waiting room. Small miracles -- if I'd heard her correctly and known the hernia check was coming, I may well have gotten an erection in anticipation, which thankfully didn't happen when he surprised me by asking me to drop my shorts.
During the car ride home, my obviously irritated mother shared that this doctor had a parent/chaperone policy only for kids under 16. She said she noticed I was still dressed when she walked by, and she asked if I had to get undressed for the doctor. I told her I didn't have to take off my clothes like at the pediatrician, but asked why my brother was in a gown. She said he had to put on the gown for the walk down the hall to the x-ray, and I asked if he was in just his undies for the rest, and she said yes, until the doctor came in. It seems that he got the pediatrician treatment at 14 at that family practitioner, while I got the adult treatment. But she pivoted back to me and said, "I told the nurse that you had a heart murmur and were a late bloomer, and for the doctor to check both. Did he not listen to your heart? Did he not look at your peepee?" I replied that the doctor used the stethescope on me, but over my shirt, and he did make me drop my shorts and undies for a hernia test. She said, "So he did see your peepee? Did he say anything about your peepee?" Exasperated, I said, "Yes, he saw it, and didn't say anything was wrong, and stop saying 'peepee,' Mom! I'm almost 17!" She still seemed irritated, but she dropped it, at least for that car ride home. My brother, still mortified from his experience, and probably jealous that I got the grown-up treatment, didn't say a word.