Common colloquial American phrases will not mean much to a person who does not live in the United States. Telling a colleague that he or she should "go for it" will not take anyone anywhere and saying someone is "out of the loop" will likely put you there.
We've covered World Englishes (as they're often called) in previous posts, so if you want to stay ahead of the game...sorry, prepare so you are ready when we start this unit... have a look at these links:
The End of English - David Crystal's take on World English
French, English and American
Dirty English infects beautiful Italian