what is your initial reaction when you are being told to be an idiot?

Consider the source to be the idiot and just move on.

People with tact won't call you an idiot but generally an idiot will call you an idiot.

I would just say..." No thank you. And walk away."

I would not be friends with someone like that.

They have no tact.

As I recently replied to another question, "what other people think of me is none of my business", and "no one can make you sad without your permission". Good advice to have and internalize, speaking for myself.

As for "justified retaliation" - again in my life, what applies to my path leading to a desired stage, I discovered "negatives" (as I define them) would invariably detour me, little by little until I'd be walking wherever except towards my goal. These "negatives" not only are what would normally qualify as negative but even "justified" expressions such as "justified anger", "justified revenge/retaliation" and other socially-condoned reactions. Some might argue if justified then do it, but in my case proved when justified consider the path in Life it will open if indulged - in my case the path would always prove "justifiably being detoured away from where I desire to go".

Takes time and practice to become adept at handling situations in a healthy manner, instead of allowing nasty situations to adapt you to nastyness.

There's a story of a native who found an eagle egg that fell out of its nest. Being unable to put it back, decided to add it to a nest with prairie chicken eggs. The prairie chicken upon return, sat on it as if hers, until the eagle hatched along with chicklets. Growing up, he learned to scratch in the dirt for worms, to fly short distances like chickens frantically flapping their small wings. One day, the now mature eagle looked up and saw a majestic bird soar through the heavens, and he so wished to be such a bird flying by the side of that bird above. Turning to his chicken neighbors and siblings, he asked them "what is that graceful bird soaring across the sky called?", and the chickens clucked "that's an eagle, the king of all birds, give up any hope of being like that, you're just a chicken". And so, the chicken-raised eagle went back to scratching in the dirt, clucking, and pining away on account of what he never can be. He lived with a chicken identity, dying as a prairie chicken instead as the king of birds he was all along.

All human beings are majestic eagles, but, the prairie-chicken world not only persuades us we're stupid, useless, worthless chickens, but tries to keep us grounded, to live like chickens. You ask about hurtful comments of others, and about justified retaliation - had I went that path, to this day I would think I'm but a prairie chicken, but, instead now know better and even soar with new outlook on life below. The choice is simplistic almost - do you wish to believe the world's lie you are worthless, or, realize intrinsic human worth as a child of God? Even if you're not religious, you still are an eagle not a prairie chicken - takes an inspired eagle to recognise an eagle, at least to this extent I tell you that much, namely, don't believe world's dehumanizing lies. -Pat

(edited due to typos related to typing on my tiny cell phone's virtual keyboard)