The first time Crimson Knights has any nudity it is in the form of the extremely unsexy Ajattara, which is an undead witch monster.
Drowtales has several instances of this, and given that there's an entire section of the site dedicated to unironic Fanservice the Fan Disservice stands out.
One page featured fan-favorite Naal'suul for part of chapter 13 sans-clothing (though you can't see anything) the disservice comes from her body language and posture due to being imprisoned in a dark cell, and the fact that she's talking about the demon that already Mind Raped her once and will eventually take advantage of her again and kill her.
Also, Kharla'ggen. She wears low-cut tops with Navel-Deep Neckline and is seen in a bathhere and here, but she is completely insane with a childish personality and a sinister full-face mask. She is also horribly powerful, which she often manifests in another example: her cutely-costumed life-size dollies, which she makes from real people... just by thinking at them; the transformation leaves them conscious but (usually) immobile and, as far as anyone can tell, is irreversible.
And one of the few times we see fully uncovered, uncensored breasts in the main archive is... on a possessed pregnant woman, whose fetus is reaching out of her stomach and is also possessed. EUGH.
There's also the beautiful, uncovered body of Sharess, the sexiness of which is mitigated by the fact that she's a thousand year old corpse.
The crowning moment so far has to be Chapter 32, which opens with a love scene between Lulianne and Rek'mar and goes from "sweet" to "OMG WTF" in the space of a page. Thanks a lot, Khaless.
And a grown up Naal proves to be quite well stacked and gets a scene with her chest completely uncovered. Too bad she's, you know, a demon and her bottom half is made of the corpses of people she's absorbed over the years. And even after this, when she takes over the body of a Sullisin'rune spy, Iliva'fay, who's quite well stacked and wearing a dress with a prominent Cleavage Window, she ends up with a second mouth on her stomach with teeth and a mind of its own.
Exploitation Now has a brilliant use of this. Underage Villain Jordan had been the number one request for nude fan service for the length of the story arc, but when the artist finally did so, she was being raped by a former class-mate turned pathetic wannabe villain.
Whenever there is nudity in Flipside, there is about a fifty percent probability it will occur in a not at all erotic context, for example Maytag being stripped and forced into a collar by a magically-enhanced psychopath intending to rape and kill her.
In General Protection Fault, Trudy has a dream of an... intimate encounter with Nick. When all is said and done, she calls out to him as they lie on the bed naked, only for him to suddenly be replaced by Ki, then Fooker, then Nefarious, then Todd, then Chuck, then her future self. Nefarious and her future self are old and quite wrinkled, and Trudy's future self has some horrific expressions on her face.
Occasional strips where Abbey appears topless. Since Abbey is horribly malnourished, this is very disservice-y. The worst is definitely the first time, when Abbey is downright skeletal and her chest is rotting from the inside due to a bad case of Phlebotinum Breakdown. On later occasions she looks slightly better, but never enough to qualify for actual fanservice.
Not to mention later strips with the hideous growth of insectile wings protruding from her back.
Goblins has Cute Monster Girl Saves leaning into a dome that makes everything within its volume invisible. Dies gets a brief glimpse of heaven as it clips through her shirt... and then he gets a look at her internal anatomy when it clips through her face and torso.
The Grim Tales from Down Below comic has a disturbing picture of an adult Mandy, and an even more disturbing dialogue, as Nergal mentions that the only way Grim could have an undead skeleton son was by aborting an actual infant.
In How to Raise Your Teenage Dragon, Steely Dan's outfits are often kinky or sexual in nature, and very revealing, however due to Steely's pure white skin and her manic facial features, these outfits tend to come off as unsettling instead of sexy.
Leslie and Brianne: The title characters often appear nude or scantily clad, but the crude Microsoft Paint artwork (combined with the girls' slovenly habits) makes it clear that it's Played for Laughs.
In this◊ episode of Looking for Group, we get to see under the dress of one of the main characters... It's the rotting undead male warlock.
In Misfile, there is a shot of a very attractive, physiologically female character, fully-frontally nude, with only two very, very thin panes breaks hiding said character's nipples and crotch. The catch? He's in the middle of a majorHeroic BSoD, because of the exact qualities of that same body that would appeal to people attracted to women.
Oglaf is laden with explicit sex of all kinds...including a giant spider giving head, molten hot succubis (literally), etc.
Penny Arcade. September 19, 2007. Tycho gives Gabe an unfortunate mental image in retaliation for Gushing about the then-upcoming Mass Effect (and more specifically, the scene that the hubbub was about). Of course, bothering each other with unfortunate mental images is just one of the things they do. And yes, there is a reference to this later for the sequel.
Or this page lampshades the concept of fan disservice with elderly nudes. It's more in-universe though, since the readers are spared the worst, unlike poor Faye.
In universe verbal example. The ladies at Coffee of Doom are having a contest: who can say the worst thing during sex. Martin wins with "Happy Birthday, Grandma!"
And later there's Kusari doing an homage to the Coppertone baby ad. It would be just plain old Fanservice, except that the dog who pulled down her pants... well, let's just say Kusari has an itchy scythe-finger.
Terinu has a lengthy sequence with Gwen dressed in an "Exotic Dancer Barbie" outfit. In the very last panel we're looking behind her and she's standing half-naked in front of two ancient aliens literally twice her size, making her appear twelve years old instead of fifteen (which would be bad enough).
Unsounded: An image of Roger having passionate sex with Mallory is shown, which is obscured by images of Roger being dissolved and Ruck's dripping fangs, accompanied by Ruck cruelly mocking Roger for having human desires while Roger's wounded, empty eyed bleeding body lays on the floor with cerebrospinal fluid dripping from his nose.
The VG Cats strip "Kinder Surprise" ends with a scene of Gabe Newell swimming in a pile of money, naked. Ewwwwwwwwwwwwwwww.
In this issue of The Word Weary, John, one of the protagonists is shown nude from the back as he gets changed. While in-universe it's shown that he's not a bad-looking guy, the detail of the hair on his back and buttocks is a bit squicky.