Not always. I lived in rural SD and moved to Prince George County, MD when I was 11. I honestly didn't understand half of what the other kids were saying most of the time. There were lots of words like these but for example, I had no idea what "gay" or "fag" meant even. The thing is that I know what all those words mean now and the truth is those kids couldn't give me the right answers to almost any of the meanings of those words back then.

My favorite was when one kid called another kid a fag and when I asked what that even meant, they said it was a "burning stick." Well, that's the dictionary definition. So why would someone call someone else something stupid like that? They didn't know, it was something they heard some where else. They had no clue what it meant, kids just call each other names. It's what they do.
No, they don't usually really know.