Street slang, colloquialisms, idioms, phrasal verbs, you probably didn’t learn these in school! And if you did, you might have learned dated, unreliable, or geographically sensitive ones. Learning appropriate grammar means much more than scoring a 550 on your TOEFL because language is built for communication, not for passing standardized test. It is what it is, man.
Most educators are more than willing to provide students with definitions and examples of appropriate slang usage, and every class I’ve ever taught has dealt with idioms and phrasal verbs formally, but until you know how to speak the lingo in an understandable manner you can’t really speak the common tongue.
Listen for them! A lot of the time tone is directly associated with meaning. Listen for words that seem out of context, or groups of words that don’t seem to fit together. Listening is tough, but the more you practice the easier it gets.
Speak with native speakers as often as possible. Your filter, your confidence, and your ability to ask questions without being shy are going to be key to your success. You must remember that native speakers are going to get frustrated because their native language is so easy for them. Remember to smile and repeat what they say as often as possible. It makes them feel important to be able to answer your questions.
Don’t be afraid to practice collocations. Try them on your peers first and notice their reactions. Yes, you’re taking a chance of saying something obscene or inappropriate, but you’ll never know without making mistakes. From my experience, there is nothing easier to learn than “bad words”. They’re shocking for a reason, and they usually shock your brain into remembering them.
There’s a saying in English, “Walk softly and carry a big stick.” that applies here. Tread lightly on words that may be inappropriate, but make sure you learn them well (you know them in your own language) because “bad words” happen.
International Student Advising 