For me, my truly favorite part isn't really something the doctor or nurse perform on me, but rather the waiting to be told how they want me to disrobe. I love the anticipation, not knowing which way they'll want me to be.
Sometimes it is a disappointment, if they just have me lift my shirt, and they generally work around doing what they need to with me remaining dressed. But, more often than not it does involve some sort of undressing, and it can vary from just shirt off, to everything off except underwear, or everything off and put on gown, ( the most common, these days.)
The variations are what thrill me. And, the rare handful of times I've been asked to do some unusual bit of disrobing, are what I remember best. A few times I've been told to leave my shirt on, but I'm naked below the waist, or just in my undershirt, when I was a kid. I was mentioning in another thread, my earliest school physicals, which were in 1st, 2nd, and third grades, each involved undressing in a different way. The second year was everything off except my socks, which actually left me feeling more naked and exposed than when I was asked to take off everything completely the next year. That left a lasting impression on me, to this day. This has happened a handful of other times over the years. It's that uncertainty I love.