You dumb bro

So how do you tell someone they are dumb af?
Do you do it bluntly like "bro you're dumb af I've seen rocks smarter than you"
Do you say it with more tact?
How do you break the bad news to them? Especially if they don't know they are kinda on the dumber side and you know that telling them they are dumb will help them out. So yeah how do you tell someone they are in fact a dumb bish

 

I'm all about bluntness but I don't think this helps unless I'm genuinely trying to hurt you in the feels. Have some fucking respect. Dumb bitches have feelings too.

 

Ngl you were never like me cause then you'd be pretty awesome and ngl you not.

 

I guess I'll add some anime styled backstory.
So this person has low self esteem and they say "I'm dumb" to which I respond "nah girl, some things are challenging but it doesn't mean you dumb" but ngl they are like dumb as heck but since they have low self esteem and they look up to me, I am careful I ain't wanna crush em, like I'm not even gonna go into details but I feel like I'm just hurting them by being "tactful" and saying pretty shit to not make em feel bad , you get it boy?