Even after learning italian, you should be aware of something really scary: dialects.

Jokes apart, in Italy there are really a lot of dialects and even for italians it is hard (and sometimes impossible) to understand people that speak with their own dialect. I'm from Rome and I would like to teach you some you must know words if you plane to come and stay in Rome for both a short or long period of time:

- Scialla: it means "take it easy". We use it very often and there is even a movie staged in Rome with "Scialla" as its own title.

-Daje:

            1 you can use it when someone does something good

            Davide: "ehy Riccardo, I won 100 euros!"
            Riccardo: "daje"

           2 you can use it when you have to cheer up someone

           Davide is running toward the finishing line of a 100metres race:
           Riccardo: "daje giacomo" (in this case you should scream)

          3 you can use it as "yes" in some occasions

          Davide: "Riccardo, do you wanna go to the cinema tonight?"
          Riccardo: "daje"

- Calla: it means "lie", for example: "mi stai dicendo una calla" (calla means "bugia" in this case). We use calla also as an adjective:                     "l'acqua è calla", in this case "calla" is the Rome dialect's version of "calda". 

There are tons of other expressions but the three i wrote are the most common ones. I hope you to feel interested in this field because dialects are a part of the italian language as well!