[Trouble]

As in slang. Something that's not in the dictionary. You know how in English we don't always say yes? We say yeah, mhm, fo shizzle, etc. And in Japanese, instead of saying Hai all the time, you say eee, aaa, and such. But I want to know how to make myself sound more native and friendly rather than talking like a dictionary. And yes, I know casualness is only for my close friends, not strangers or older people.

I'm a boy.