I'm going to let someone know about the flaws in their life that they seem oblivious to.
Why would you be this blunt about their flaws?
I feel like they are not aware how much the society look down on them for these reasons
It's okay to want to be honest with someone, but just be sure you're doing so for their benefit. Try to be sincere but not too blunt to avoid hurting their feelings. They may end up respecting you for being honest with them.
Oh lol, I was just being an asshole. My friend told me to direct them to their flaws and it was fun.
Putting someone down just for your amusement is cruel. Would you like it if someone were to put you down and laugh about it afterwards? If you have nothing nice to say than just say nothing instead of ruining another person's day.