This is also posted on the Root Blog.I continue to get referrals from search engines of people searching for things like "fuck off italian version". I don't think they want to insult this blog, so I suppose they want to learn Italian swear words.
Well, in the optic of giving to my readers the service they request, I'll provide a quick guide to Italian swearing.
Fuck Off and variants are equivalent to 
Vaffanculo (the last u is pronounced as "oo") - this word is a bit hard to pronounce for English people. It has no literal meaning; sometimes is also used as interjection or expletive. Variations are 
'fanculo, 
'affanculo, 
va'nculo and others. 
Vaffanculo is the very Italian expression, but also 
fottiti has a rather widespread use.
Shit --> 
MerdaFucking is equivalent to 
Fottuto/a, but other expressions with the same meaning are 
di merda, 
del cazzo.
Son of a Bitch is expressed with 
Figlio di Puttana, but while especially Americans use it quite frequently, Italians most of the times mean it, when thay say it.
Bastard --> 
Bastardo (That's easy)
Motherfucker and variants have no exact equivalent in Italian. The gravity or rudeness of the insult is increased by adding adjectives or prefixes: 
stra-fottuto, 
brutto figlio di puttana.
Stronzo/a literally means Turd, Piece of Shit, but it's also used to indicate mean, dishonest, cheating persons. 
Stronzate/a means Bullshit, as 
Cazzate/a does. 
Fare una Cazzata/Stronzata is used as Fuck Up/ Screw Up.
Bitch/Slut/Whore --> 
Troia(Stronza)/Puttana/Maiala (Italian words ending with -a are most often feminine)
Cazzo is probably the most frequent swear word used in Italian. Its literal meaning is Cock, Dick, but it has a wide variety of uses: as Fucking or Fuck, to make a sentence more rude: 
Che Cazzo fai? instead of the normal 
Cosa fai? (What the fuck are you doing?/What are you doing?); 
Non capisci un Cazzo (You're dumb as fucking plank); 
Non ho visto un Cazzo (I did not see a fuck) etc. It is also used as interjection (that is pretty rude) or expletive.
Fucking Hell and derivatives --> 
Porca Troia/Puttana/Maiala. If you want to add empasis, just make a chain: 
Porca puttana troia lurida (Dirty) 
fottuta.
Ok, this is just a brief and disorganized glimpse into the swearing richness of Italian language. More will come, sure as hell.