Spanish is not just a language. Every Spanish-speaking country has its own ways, slangs and special words. Not to mention accents: if you speak Spanish very well (or if you were born in a Spanish-speaking country as I was), you can recognize many different accents from many different places.
Thing is: Latin America is not just one country, but many. And we all have different ways of speaking and saying things. Or at least certain things.
I am from Argentina, so the "language" I master is "Argentinian" Spanish.
Let me help you speak like us.
(Oh, BTW, if you are reading this and you're Argentinian, correct me if I'm wrong)


PRONUNCIATION

The most noticeable feature of Argentinian Spanish -which differenciate us from other countries- is one letter.
That letter is "Y".
Most Latin American people pronounce the letter "Y" as the isolated letter "E".
Like for example, a Mexican person will tell you the word "yo" (which means "I" ) as "ee-'oh". Or something like that (the apostrophe ' stands for the accented syllable).
However, we, Argentinian people, will pronounce the "Y" as "SH". So, whenever we want to say "yo", we will say "sh-'oh".
The same thing happens with the letter "LL". Yep, we have double L, which in most countries is pronounced like the Spanish "Y"; that is, like the English letter "E". But not in Argentina. We say "LL" as "SH" too. So, when a Colombian girl says "lluvia" (which means "rain" ), she will say something like "ee-'uh-viah", whereas us Argentinians will say "sh-'uh-viah".
That simple sound is what identifies us -Argentinians- from the rest of Latin America. Except from Uruguay, no other country pronounces that letter that way.
Of course, we also have intonation differences. But that is harder to explain. Much harder, I must say, and I don't think I can explain it in a post. So the main thing to know about us -as far as pronunciation goes- is what I've just told you. If you want to speak Argentinian Spanish, this is THE one thing you need to know. Every "Y" or "LL" you see, go for the sound "SH".


SLANG, SAYINGS AND OTHER STUFF

SLANG
We have some words which no other country uses. Let me teach you some of them.

Che
Like "Che Guevara". Actually, that's why people call him that way: because he was born in Argentina.
This is our "most local" word, and it has no exact translation. It's an interjection, like when you American, British, Australian people say "hey" or "dude".
Examples:
"Hey, how are you?" ---- "Che, ¿cómo estás?"
"Dude, can you lend me that?" ---- "Che, ¿me prestás eso?"
Lemme tell you, we use it ALL the time, so you may as well bear that word in mind

Gil
This word means "stupid". You do not want to say that to somedoby you like. Although I must say, sometimes we use it in a not so insulting way. For example, you may say something like "no seas gil, eso no es así", which would mean "don't be silly, it's not like that".
Basically, it has a lot to do with the intention you give to the sentence you say. But it can be pretty aggressive, keep that in mind.

Gamba: This means "leg". It can also mean "a hundred bucks".

Birra: Beer

Mina: Girl, woman

Chabón: Guy, man

Guita, Tarasca: Money

Quilombo
We use this word when we talk about a problem. When something is a mess, or it's really problematic, we say it's a "quilombo". We also use this word to say that something or somewhere is very noisy, or crowded, or confusing.

Porro, churro, Caño: pot, joint (as in marijuana, he-he)

Pibe, Piba
This word means "kid". In Spanish, "pibe" would be male and "piba" would be female.

Boludo, Boluda
Again, the "o" is male and the "a" is female.
This word is difficult to explain.
"Boludo" was first intended to mean "asshole" (sorry for the bad word). And sometimes it actually means that. But MANY other times this is just a harmless expression, very similar to "Che".
We can say something like "Che, boludo, vamos al cine", which would mean something close to "Hey dude, let's go to the movies".
"Boludo" is a very common expression in Argentina. But then again, it all depends on your intentions. If you tell someone "vos sos un boludo", that would mean "you are an idiot". Very different from when you say "dude", huh? So it really comes up to what you want to express. If you mean well, then it won't be any problems. If you mean to insult somebody, well... you probably will.

Chamuyo, sarasa
These two words have the same meaning. They mean: "crap" or "lie".
We use these words when we want to express that someone is scamming us or lying to us, trying to mess with us, when somebody is not being honest with us.
Example: "Come on, man, this is crap" ---- "Dale, che, esto es chamuyo"

Afanar, Chorear: To rob

Choto
This means "bad", of bad quality, cheap. You can refer to something as "choto", meaning that that something is very bad.
But we use that word not only for products. When a situation is bad or unpleasant for us, we can also refer to it as "choto".
And again, we have gender for this word. If it is male, it will be "choto". If it is female, it will be "chota".

Morfar, Lastrar: To eat.


SAYINGS AND OTHER STUFF
We all have ways to say certain things. Not all of us say things in the same way. We Argentinians have a special way to talk about some stuff. Lemme tell you some of them.

No me rompas las bolas
We say this when we want to tell someone that we don't want to be bothered. Actually, it's what it means: "don't bother me".

Qué hacés, boludo?
This is how we say hello many times. It's like saying "Hey dude, how are you?"

Me colgué
It would mean that you got absent for a moment.

Esto está joya
When we say this, we mean that something is really great.

Estar al pedo
Means having nothing to do

Estar embolado
This means to be bored

Una banda, una bocha
"Una banda/una bocha" means "a lot"

No me jodas
Don't bohter me. It can also mean surprise. Like for example: "No kidding, are you serious?" ---- "No me jodas, ¿en serio?"

La posta
Hard to explain. We use this expression when we want to make clear that something is THE truth.
Example: "This is the real thing, this is the truth" ---- "Esto es la posta".

No me cabe
I don't like it.

Tenerla clara
To know something, to understand something clearly.

Me tengo que rajar
I have to go now.

Mala leche
This expression can mean two things:
Bad luck
Or "mean intentions".
It depends on the context you are using it because it's indisctinct: you can use it for one thing or for the other. So be careful when you say it!

Es una masa!
It's great!

Es un flash
It's unbelievable, it's surprising, it's astonishing.

Me importa un carajo
I don't give a damn.


Well, this is some Argentinian Spanish for you. It's not everything I've got but I think it's the basics. If you ever want to visit my beautiful and beloved country, these things will help you get by.
If you want to know any more stuff just let me know. I'll be happy to help you


THANK YOU FOR PASSING BY.
SEE YOU!