Which led to a hilarious adaptation in Italian where "razzo" (rocket), was used instead of "cazzo" (cock, an actual Italian interjection used in similar way to the English "crap!")...nobody was able to see Marvel 2099 characters ejaculating "Rocket!" in front of flabbergasting or intense situation with a straight face.
Spider-Man 2099 writer Peter David said he had considered introducing "shuck" as another futuristic epithet, on the grounds that it was a combination of "shit" and "fuck".
The Dark Knight Returns features some truly bizarre slang, including "ace" for lose (as in, "aced the coat and now I'm freezing), "billy" for "crazy", "chicken legs" for "attractive young female" and "don't shiv" for "don't take no shit."
Zodon: What the Gumball did you do to me, you Windshield?!
Herschel: I just gave you what I call a "Barry Ween" chip. We can shut it off if you learn to tone down the cussing, and it'll dissolve completely when you turn 18.
Zodon: You Flower Garden, I'll Fox Trot all over your Drinking Fountain! Umbrella! Crunchberries! Cordless Telephone!
And if he gets really upset and starts swearing non-stop, the chip causes him to sing show tunes.
And in Aaron Williams' earlier comic work Nodwick, there was a short story arc about marketing the hottest new swear word - KRUTZ! It's because two necromancers need a word of power said more times than they can hope to themselves in any reasonable amount of time.
"Grud" is a Mega-City corruption of 'God'. The Vatican, which is a police state equivalent to a Catholic Mega-City, sort-of worships him, although the majority of high-ranking members of the Vatican's establishment seem to not care either way.
Now that 2000AD (Judge Dredd's parent comic) isn't exclusively aimed at children, real swearing has started to creep in, though it's still peppered with the odd Drokk every now and then for good measure.
Sinister Dexter, another 2000 AD comic, presents "funt" as the curse of choice in the future pan-European city of Downlode. No definition is ever given, and, aside from the obvious variations such as "funting", several more unsual forms appear, such as "smugfunt" and "funtwipe", further enhancing the ambiguity of the word. Given the often tongue-in-cheek nature of the series, it is likely that this is, at least in part, a nod to similar practices in other sources, particularly earlier 2000AD strips.
The Legion of Super-Heroes comic had a variety of alternate swear words, including "Pain in the klordny", which an editor translated as "neck" when challenged on it. Why "pain in the neck" would need a euphemism was unanswered, and later usage included "get off your klordny"... There was also a completely unexplained "klordny week" holiday/festival... which is probably better not thought about much.
Most of them are used inconsistently. "Sprock" usually means what it ends like, but "Sprock happens" once appeared. "Grife" appears to be the name of a deity - never used except as a curse. And on occasion, curses from other universes are used (Oh, frak.")
At one point the frequency of futuristic swear words was lampshaded in a fictional interview with the Legion's police liaison, who commented that those kids had the filthiest mouths she'd ever heard.
Lobo's all-purpose curses are "frag" (a real term for killing with shrapnel) and "bastich".
Bastich (or bastiche if you're feeling highbrow) is a combination of Bastard and Bitch generated out of necessity: When encountering as many alien species as The Main Man, one cannot always be sure of the gender of the person one is insulting.
Izzafact? Feetals Gizzard! note In the German version: Rostiger Röhrenpilz! It's almost poetic.
In a Peter David-penned Hulk series, "flark" was used as a Future Slang f-bomb; later, Genis's own circle of friends began using it in the present as alien slang.
Averted in Madman, in which the titular character is unable to curse due to an unknown issue.
Captain Haddock from Tintin used a variety of very creative oaths, mostly variations on "Blistering barnacles!" and "Thundering typhoons!" There's actually a list of them here. ("Bashi-bazouks!" "Lubberscum!" "Coelacanth!" "Diplodocus!") The ultimate would probably be "Billions of bilious blue blistering barnacles in a thundering typhoon!"
Another 2000 AD example, Shakara, features 'frukk', as in "Oh, frukk!" and "Get that frukker!"
Strontium Dog initially used Dok for God. When is moved over to 2000 AD, it started using the same curses as Judge Dredd. With one notable exception—Strontium Dog has "Sneck" as its "Fuck" Equivalent. For the inhabitants of Mega-City One it's "drokk".
Yet another example from 2000AD (who seem to be in love with this Trope): In it's early days Pat Mills' Savage made use of Funk as a replacement for "Fuck." This was quite an unusual decision, since Savage not only used regular swearing, but the strip debuted after swearing had become less of an issue in the comic (although it was a direct sequel to a strip from the '70s) and it initially had a much more realistic and grim tone than it's peers listed here. Usage of the term has since disappeared, however.
In Spain, these are known as "Bruguera insults", a reference to the children's comic book publisher Bruguera, which essentially owned the Spanish market between 1940 and late 1980. The fact that they spent the majority of those years under Francoist rule meant that there always was a censor looking at every single word waiting to be printed, and for them, even Gosh Dang It to Heck! was over the line. Since Spaniards are known for loving their profanities, the writers had to resort to making up words that would pass the filters but would kind of sound like actual insults and curses. "Que me aspen", "retruécanos", "merluzo", "percebe", "batracio", "botarate", "tontaina" and a ridiculously long list were used for those 40+ years, until the company filed for bankrupcy (and still are used in their two surviving series, Mortadelo y Filemón and Superlópez, as an homage to their roots, despite publishers nowadays being fine with anything short of a Cluster F-Bomb).