Where I work everyone shares the same open office. It’s also a middle school. So make my vote a heeeelll no.
While I’m in a cube farm these days, I’ve had my own private* office a few times along the way, and more often than that been in a shared office that was private other than that, and was safe to change in after my officemates had left for the day. Which I did.
*Private for the purposes of this thread, i.e. you don’t share it with anyone, you can lock the door, and no one outside can see you when the door’s shut.
Yes. And a couple of times, I was lucky enough to have a lady gettin’ nekkid with me. 
Since I’ve never had an office and I’m a bit too shy to strip down in a cubicle, I voted no. But the last place I worked before retiring had locker rooms with showers, so there was no reason to get nekkid anywhere else.
Yes, for exactly the same reason as the OP: Bicycle commuter. Before I got a promotion and an office with a door, I used to use a small conference room to change in the afternoon.
Frequently, but it’s a home office. I’ve even talked to clients on the phone while au naturel! (Not video calls . . .)
Partially, and it was my boss’s office.
Um, I should probably explain that ;).
- he was gay, and not remotely interested in anything I had to offer
- He was not in the office at the time, and
- I was using it to pump milk for my infant daughter.
He was a bit startled to come in one day (a day he was not normally at work) and find a sign saying KNOCK BEFORE ENTERING on his own door. Fortunately for both of us, he did in fact knock.
There was a story, many years ago, in the City Paper (I think) by a man detailing all the trials and tribulations he and his wife went through to try to get pregnant. There was the day he needed to produce a fresh sample. He didn’t have an office of his own, but his boss never came in early so he decided to take advantage of the empty room.
More precisely she never came in early before (or ever again, I’d imagine).
My office is my living room, so yes, many times.
Other.
I’ve never worked in an office, but one miserably hot and humid afternoon I was working on a piano, had the non-air conditioned building to myself (working in the shop behind the showroom). I locked the front doors, put up the CLOSED sign, and worked butt-nekkid for a couple of hours. I was a lot more comfortable physically, but felt sillier than shit.