Just like a pregnant person = yes
Do you have to disrobe? = no just undo the front of your pants
I know I have to come with a slightly full bladder, but I’m curious what it is like.= likely they will ask you to pee and then they will use the ultrasound to check how much is left in your bladder.
Can I keep a diaper on? =You will likely have to pull the front down
if you use a diaper with Velcro tabs, you can just pull the top tabs lose and fold it down. And they will put a gel on, then run the ultrasound.
They want to see how much is retained in the bladder. And maybe the size of your prostate.
It's fun if you have a cute lady doc doing it.