I always take care to select a pair of underwear that I'd like to have seen when I go to the doctor. I distinctly remember underwear choices from visits to my pediatrician.
Once when I was quite young, I wore a pair of camouflage-print briefs on the day of my checkup. Weeks later, I was changing for gym class or at the pool wearing the same underwear. I recall, even then, having a realization about the sharp difference in environments. I though: "This is exactly how I was dressed for the doctor". I was immediately aware of the different attitudes when wearing that same outfit -- in the changing room, it was all about trying to stay covered up and modest while at the doctor's office, the whole point was for him to see me all over.
I switched from "tighty-whities" to boxer shorts around 6th grade, and my options opened up considerably then. I had many different colors and shapes to choose from.
My first exam in boxers was a pair of red plaid flannel shorts. I almost never wear flannel as underwear anymore because they're impractical -- they cling to my pants and bunch up. But back then, I was super excited to get a little bit of extra coverage at the doctor's office. I had figured out a way to beat the system by actually wearing *shorts* during my exam! What I hadn't considered, though, was that this pair was the style that didn't have a button fly -- just two sometimes overlapping pieces of fabric, so when I lay down on the exam table, the movement had caused my penis to poke through the fly! My doctor was super cool about it, though, not even acknowledging it and actually doing the genital and hernia exams through my fly instead of lowering my boxers.
Another memorable exam/underwear combination was my first exam by myself in which I wore a pair of plain green boxer shorts and became embarrassed when the doctor asked me to stand, and when I did, my erection pushed against the fabric, making a tent. He then had me pull them down and stand in front of him for the genital and hernia exams while he showed me in great detail how to perform a testicular self exam.
Other boxers I've worn to the doctor's office include a pair with Loony Tunes cartoon character faces printed all over, a black-and-white plaid pair with a cartoon character embroidered on the leg, and a bright yellow pair with little monkeys printed all over them.
It's been several years since I've been to the doctor, but I'm actively seeking out a new one for a physical. I'm unsure of which underwear I'll choose for that first exam, though. Day to day, I like to wear boxer briefs and have a few pairs in some fun colors, but a more traditional pair of baggy boxers might be more comfortable and offer a little more coverage in that scenario -- they'd also allow me to express myself a bit more with a wide range of colors and prints. Any thoughts or advice?