Swear words that aren't derived from Earth-speak but rather from within the Star Wars universe's context alone e.g. sithspit
While not comprehensive, http://starwars.wikia.com/wiki/List_of_phrases_and_slang offers a fairly impressive listing. Of note:
Bantha fodder: The equivalent of "worthless"; a person or thing deemed to have no value beyond something for a bantha to graze on.
Choobies: A slang term for one's self or one's testicles.
Dosh: An expletive used to express anger.
Doshing: A derogatory modifier, as in "Take your doshin' hands off."
E chu ta: A term spoken to C-3PO by E-3PO on Cloud City to which he replies, "How rude."
Feed the Sarlacc: To use the toilet.
Karabast: A Lasat exclamation of frustration. Garazeb Orrelios was fond of using this exclamation.
Kriffing: This was an expletive. When Beck Ollet described a referee as being "crooked as a kriffing Hutt," he was ordered off the grav-ball field with the threat of suspension otherwise.
Kung: This was Huttese for "scum," i.e. "U kulle rah doe kankee kung," meaning "You are my kind of scum."
Moof-milker: A term for a dimwitted individual.
Mother of Kwath!: This was an exclamation of aggravation.
Nerfherder: An insult once used by Princess Leia Organa. It referred to the animal by the same name.
Nerve Burner: This insult suggested one was unstable.
Not the brightest lightsaber in the galaxy: Unintelligent.
Not the brightest star in the sky: Unintelligent.
Peedunky: This Huttese insult was roughly equivalent to "punk."
Piston-head: This derogratory phrase was sometimes used to describe IG-86 sentinel droids.
Poodoo: A Huttese term meaning "fodder," a coarse type of food for livestock. Used often as a swear word.
Pfassk: An adaptable expletive, as in "What the pfassk does sorry do for anyone?"
Skug: A common Zygerrian insult.
Sleemo: This Huttese insult was pronounced slay-mo and translated as "slimeball," a rude insult.
Son of a bantha: This insult was once directed at Han Solo by Sana Starros.
Stang: This slang term of frustration was once employed by Beck Ollet during a grav-ball match in reference to the opposing team's wing striker.
Svaper: Frid Kelio once referred to the athletic director Janus Fhurek as a "dirty svaper."
Tailhead: This was a derogatory slang term referring to members of the Twi'lek race.
Walking carpet: Leia Organa once applied this insulting term to Chewbacca in reference to his shaggy coat of fur.
Wastoid: A derogatory term.
One that I have come across in the EU is 'Sithspawn'
I first came across this in the Michael A. Stackpole novel X-Wing: Rogue Squadron. Lieutenant Corran Horn (Rogue 9 of Rogue Squadron) thinks to himself
Great, all I need is some Sithspawn hotshot pilot in that squint"
Note that this is Rebel pilot slang. An 'Eyeball' is a standard TIE fighter, a 'Squint' is a TIE interceptor, a 'dupe' is a TIE bomber & 'Bright' is a TIE Advanced (Darth Vader's personal TIE fighter).