Argentines love language; they are constantly playing with it, massaging it, advancing it. Lunfardo, or Argentine slang, has been much reported elsewhere.

Often, folks arrive in this country to find that the Spanish they learned in school is nowhere to be heard.

The first questions a local may ask you - “como andas?,” “todo bien?” and “de donde sos?” - aren’t usualy tought in Spanish 101 (where you may have learned to respond to “Que tal?”, “Como estas?” and “De donde eres?”).

When in doubt, the first question thrown your way is usually some version of ‘how are you’, and a great answer is ‘todo bien, gracias‘.

Well, like the quick-witted nature of just about every aspect of Argentine culture, one must keep up. Let’s take ‘cool/good/right-on’ as an example. Old slang words like ‘macanudo‘ and ‘piola‘ have done their time and been retired. Even ‘barbaro‘ and ‘copado‘ are a bit yesterday, although ‘buenisimo‘ seems to be as strong and favoured as ever. Lately, though, the right-on kids are favouring a new tidbit:
De una: As good as it gets, or top. When you tell someone about something good, they’ll nod in agreement and say ‘de una’. If you ask them how the fall climbing was, they can say it was ‘de una’. If you establish a 9pm-reunion for beers and they agree, they’ll say ‘de una’. It’s a kind of thumbs up. Another option would be ‘divino’.
I also want to mention re top: Someone who is ‘re top’ is super, super trendy. ‘Re’, of course, is Argentine for ‘muy’ meaning very. Usually, it’s the ‘chetos‘ (the snobby fashionable folks) who are ‘re top’, although a dirtbag patagonian with a cool jacket can easily be ‘re top’. Someone who is just posing as ‘re top’ could be called a ‘canchero‘, although that can be a positive word in some circumstances.
Try these phrases out. Put a radar on them to make note of when they’re used, by whom and how. Then it’s all up to you to put them to work.  Todo bien?