From that group I'd have to say that my favorites would be "accidental" and "obliged" nudity.
Japanese manga sometimes explores obliged nudity in an interesting way. A common theme is having badguys threatening to do something terrible unless the news lady/ singer/ buxom lady cop gets naked, usually in a very visible public place. You don't see it much outside of Japan, which is a shame.
Related themes that I enjoy that don't appear on that list:
"Subversive": Where there is some element of trickery involved in the subject's nudity. A good example of this would be that skit from "Bizarre" (subversive nudity was pretty much the show's bread and butter
) where they're interviewing a woman about how she's against nudity on television, then tell her that she's got a spot of makeup on her blouse. They give her a new blouse to put on behind a screen, and film her changing behind it. The woman is never aware that anyone can see her, so there's no reaction on her part, but the context of the scene tells us that we're seeing something that the subject would not ordinarily divulge.
Another example of this would be the airport security scanner from "Airplane II: The Sequel" where the women walk through the scanner clothed, but appear naked on the screen. The joke is that the men walking through the scanner appear fully clothed on the screen, thus making it an excellent, excellent, scanner.
"Oblivious": This one is exceedingly rare: It's when the subject, for whatever reason, be it magic or sheer suspension of disbelief, is denuded but continues to go about their business without appearing to notice that it's happening. Usually it's just an extended delayed reaction before the subject realises their plight and reacts. But in some cases there will be a supernatural element that prevents the subject from ever cluing to what's happening. You don't see it much in mainstream media (although I'm sure there must be examples or I wouldn't be obsessed with it
) but it crops up now and again in Japan.
An old National Lampoon magazine "Foto Funnies" segment that summed it up pretty well. There's a hippie woman playing a guitar in New York. As she plays, the passers by take her guitar case, her guitar, then her clothes, while all the time she continues to sing. At least that's how I remember it, it's been years since I've seen it and I'd imagine it's out of print.
I also saw a video online from a Japanese, I guess it must have been a porn video, where a woman was reading poetry in front of an audience while some guy wanders up behind her and takes her clothes off. She keeps reading and the audience keeps listening as if he wasn't there.
Like I said, not a very common one, but one I like nonetheless.