"You're so ghetto"
"She's such a slut"
"That's so gay"
"I was so bad today"
They show you how important it is to eliminate those phrases from our vocabulary because they are offensive and disrespectful. In some way we all know this, but sometimes we choose to ignore it. So it's great to read it somewhere so we can create more of a conscience when it comes to this issues.
The word I didn't understand was preachy. It means tediously or pretentiously didactic.
Teen Vogue: www.teenvogue.com/story/most-overused-offensive-phrases