People like to swear, and in fictional worlds they use fictional words. These are the fictional words which is invented by sci-fi and fantasy writers to add nuance to the fictional cultures in their work, and sometimes as a form of censorship (or gettings around it)- via Wikipedia.
For instance, fictional words like bitca from 'Buffy the Vampire Slayer' TV series, curse word for a girl who's deliberately cruel; flatscan which is used by mutants from 'X-men' to address humans; while scrote means "balls" from the movie 'Back to the Future Part II'.
Get the full list of fictional swear words here. Thoddo..! Where's did I place my files?? ;)