Sexual swearwords: Get sexy with your Spanish!
Coño, carajo. These can express surprise, anger or simply be used to give emphasis. Literally they are the female and male (respectively) private parts. They're much more widely used metaphorically in a naughty rather than rude sense, nothing like their literal translation in English.
Example: ¡Coño, qué hambre tengo!  Damn, I'm hungry! ¿Vienes de una vez, coño?  For heaven's sake, are you coming or not?
¿Qué/cómo/dónde coño... ?  What/how/where the hell... ?
Example: ¿Dónde coño están las llaves?  Where the hell are the keys?
Un coñazo  Lit. A giant vagina. A real pain (figuratively speaking).
Example: Este tío es un verdadero coñazo  This guy is a real pain.
Joder (also pronounced joer)  Literally it has the same meaning as "fuck," but it's more often used with its figurative meanings. It usually means to "screw" something or to be "screwed up".
Example: ¡Ya la han jodido!  They've already screwed it up! Nos han jodido con tantos impuestos  They've screwed us with so many taxes.
Joder on its own is used exactly like coño above, to indicate surprise, anger or admiration.
Example: ¡Joder, cómo llueve!  Hell, it's pooring!
Jopé, jopelines, jolines, jolín  These are a few euphemisms to replace joder. They're usually used by children or adults who want to avoid swearing.
Puta  Short for prostituta. At times it's used in its proper sense, but more often as a very strong insult, especially if a family connection is made, in phrases that would translate as "son of a prostitute" or "your prostitute mother". However, it's actually more commonly resorted to as an adjective to express anger.
Puto/a (as an adjective and always in front of the noun).
Example: Tengo que ir al puto médico  Lit. I have to go to the prostitute doctor. I have to go to the fucking doctor.
... de puta madre  Lit. ... of prostitute mother. Although it may sound contradictory, this is a praising expression meaning "very good" or "excellent". It can be applied to people and things.
Tiene un coche de puta madre  Lit. He has a car of prostitute mother. He has a fantastic car.
Warning! - do not confuse ... de puta madre with tu puta madre , which is an expression used as an insult, usually a rude reply to someone who's already insulted you.
Hijo/a de puta  Lit. Son/daughter of a whore. Son of a bitch.
Depending on the context, tone and how well you get on with the person you're talking to it may or may not be used as an insult.
Huevos, cojones, pelotas  Huevos literally means "eggs" and pelotas are "balls", but these words are also slang for "testicles" (cojones). The expressions with these words are endless and in many instances you can use either word. Following are a few useful expressions, but don't be surprised if you hear testicles mentioned in other contexts!
Example: Estar hasta los huevos/cojones de ...  Lit. To be up to the eggs/testicles with... To be fed up with... Estoy hasta los huevos/cojones de Arturo  I've had enough of Arturo.
Tener huevos/cojones  Lit. To have eggs/testicles. To be brave.
Example: Para hacer eso hay que tener muchos huevos  To do that you really need to have the balls.
¡Y un huevo/cojón!  Lit. And an egg/testicle! The meaning is similar to the English "Yeah, right!" or "No way!" but a bit ruder.
Example: ¡Y un cojón me voy a levantar yo a las 7 para ayudarle!  No way am I getting up at 7 to help him!
Por huevos/cojones  Lit. For eggs/testicles. It means a reason is not required for someone to do something.
Example: Tiene que venir a las 8 por huevos  Lit. S/he has to come at 8 for eggs. S/he has to come at 8 because s/he has to.
Costar un huevo  Lit. To cost an egg. Used to indicate that something is very expensive.
Example: Este abrigo me costó un huevo  This coat cost me a fortune.