Basic Trope: Character (usually female) has no nudity taboo.
Alice doesn't wear clothing unless asked, reminded, or if she is uncomfortable due to weather or other effects.
Alice can take clothing or leave it. She has little qualms about being nude or partially nude around other people, even strangers of the opposite sex. This extends to public places, but only if she is not asked to do otherwise. She will, however, wear safety gear such as an apron, gloves, a warm coat or shoes when appropriate.
Exaggerated: Alice never wears clothes, no matter the situation. She suffers no ill effects from it and outside of people being attracted to her, no one ever notices, complains, or treats her differently.
Alice consistently dresses in barely enough to cover herself, yet doesn't seem to understand why everyone keeps looking at her...
Alice has a strange medical condition. Maybe she's violently allergic to all known fabrics, or maybe she has a thermoregulatory condition that makes it dangerous for her body to be too warm. Whatever it is, it effectively prevents her from wearing clothes for medical reasons, and she'd rather be naked than dead.
Alice has an excessive nudity taboo, and thus is hyper-paranoid about exposing anything, so she wears an outfit the conceals her entire body, including her hair and eyes, and is very private about things that require part of her to be uncovered... Like eating! What if someone saw her mouth? Or worse, her tongue!
Subverted: Alice is Naked on Arrival, yet tries to get dressed as soon as possible...
Double Subverted: ...Only she is a nudist and just wanted clothes because she was cold.
It's not (just) Alice who saunters around naked; so does her boyfriend Bob. The heroes go to leer at Alice, only to have Bob intercept them drag them off for naked bowling.
Only one guy ever notices anything's odd about Alice, and keeps getting blamed for her nudity whenever he tries to explain or complain. As Exaggerated above, people simply don't notice that Alice is nude unless he brings it up, are quick to explain it away or forget about it, et cetera, et cetera.
Everyone and their mother knows about Alice, but she's never shown on screen.
... And one guy is constantly just barely missing his chance to meet her, too.
... Or he shows up right after someone else has explained the taboo to her, causing her to stop her previously risqué actions.
And every new scene she's unknowingly naked again until somebody reminds her and she freaks out again.
Zig Zagged: Alice is pulled aside and asked to put on clothing, but still utterly fails to grasp even the most basic concepts of the nudity taboo. She wears clothing when asked, only to wear it incorrectly, insufficiently, or inappropriately. And that's when she remembers at all, as she still requires frequent reminders about which type of clothing is appropriate where.
Averted: Alice grasps the nudity taboo fairly easily, and while she doesn't share it, she respects her friends enough to fake it for their comfort.
Enforced: "The typical audience for our series comprises mainly twenty-something men, so what would be better Fanservice than someone who never wears anything?"
Lampshaded: "Let me guess, you're one of those innocent types that doesn't have the first clue about why everyone smiles when you walk into the room, right?"
Invoked: "Now all we need is to run into some cute alien girl who'll walk up and ask 'What are these strange things you call pants?'"
Brenda invites Alice to her pool party to make sure that all the guys want to be there.
Brenda invites (or simply sends) Alice to Cathy's wedding, with the intention of ruining the event.
Alice may not understand why the nudity taboo exists, but everyone else around her wears clothes, and she's not self-centered enough to cause a big ruckus just because pants are a new experience for her.
Discussed: "Why is it that every single race in Star Trek seems to have the same fashion sense as humans?"
Conversed: "In real life, that girl will get arrested, catch something, freeze—" "And you're complaining?"
Implied: Everyone goes to a costume party, after which Cathy and Denise discuss everyone's costumes except Alice's.
Alice's disbelief in wearing clothing isn't innocent cluelessness but rather a conscious belief in social nudity, and when confronted about it she becomes deeply offended at accusations of lewd conduct.
Alice is faking the innocent part — she has figured out the nudity taboo, but doesn't share it. As long as people believe she doesn't know any better, however, they leave her alone and allow her to get away with much more than she should.
Alice walks around naked in public...and then gets arrested for indecent exposure.
It's revealed that Alice's quirk is her attempt at bending The Masquerade, and the hero revealing that he can see her lets her know he has some natural immunity to the Weirdness Censor in the town.
Alice is frequently nude when in an inappropriate setting, but hates it — she suffers from vestiphobia, allergies to common cloth types, a vow of poverty/nudity, superpowers that are not conductive to modesty, a magical curse, Mind Control from a pervert, et cetera, et cetera.
A drop in temperature prevents Alice from going outside at all, keeping her sealed in a single building until spring ... or worse, she doesn't know better and goes outside anyway, which isn't a healthy thing for her to do, and her friends must nurse her back to health.
Alice has terrible feet and catches colds frequently. Also, her breasts used to be somewhat higher a few years ago.
Alice does a lot of soul searching and rejects the nudity taboo, deciding that the people watching having lewd minds is the real problem, not her and her comfort with her body.
Alice appears to get over her quirk, only to reveal that she has merely learned that it's not acceptable to be nude in public. She still has no real qualms about nudity per say, and relaxes in the nude when it's acceptable. Her friends still have to help her understand exactly when and where that is.
Played For Laughs:
Alice's new friends constantly have to remind her to cover up, and are constantly hiding her, explaining her away, asking people to ignore her, et cetera.
Alice is rendered thusly innocent via a blow to the head or other such plot hook, and her friends must protect her from humiliating herself.
Bob goes to great lengths to keep Alice from learning about the nudity taboo.
Played For Drama:
Alice isn't really innocent, instead she is being forced to act this way from a curse, hypnosis, blackmail, et cetera.
Alice is truly innocent, but someone immediately takes advantage of her, possibly violently, by people who see her as an easy target.