Slap em on the forehead with a spoon and say "Stupid!"

You just can't, in my experience.

Who is making the judgment? I find it increasingly difficult to judge others, good or bad. After all, nobody does something they believe, at the time they are doing it, that it will be the dumbest thing they have ever done. Thus, if you accept this, you can argue that we only act out of good intentions. It is only later, after the act, taht circumstances reveal to us our initial choice, the original decision has resulted in unwelcome consequences. So I ask you, are you judging the act by the consequences or by the original intent of the actor. You, after all, did not make the decision...he did. Do you know what was in his mind? Probably not. I would argue that your friend (?) is looking at the basis for his original decision and finding nothing wrong with his original thinking. Why, then, should he beat himself up because of unforseen consequences. That they may have been forseen by you or others is beside the point. Don't be so harsh on your friend. After all, he was doing the best he could. Which is all any of us can do.

Why do you care so much? It sounds as if this person has hurt you...a lot. If so, rather than telling them they're an idiot, explain your feelings. If it makes no difference, time to say goodbye. Calling people names will have no effect whatsoever....

If it is your job to take charge of this person, you should just come right out with it. Tell them like it is, but add some sugar. People like this are usually the most insecure people, which is why they put up such a big front. Try to put yourself in his shoes and imagine what you would want someone to say to you. That is what you should say. Pick your battles. Why is it so important to tell this person off? What do you hope to accomplish? Most people don't enjoy hearing negative criticisms, especially when they are true. Think about the end result if you carry out your plan Do not discuss the problem while you are angry. Wait a while and let the tension out first because dealing with it right there and then will only worsen things. Use a soft tone of voice and calm, relaxed facial expressions. If you want to tell someone off in style, you have to remain cool. Stay calm while they are exploding, turning red, sweating and raising their voice; just act natural. Smile and create an air of superiority over the other person and to show your infinite class and style. You don't have to stoop to their level. Keep your cool. It's the best way to say something unpleasant, especially to the over-confident. It's much harder to argue with level-headed reason, though they will surely try. Think of other ways to resolve the matter. Have you exhausted all options? Kill them with kindness. When someone is shouting or trying to get a rise out of you and you want to tell them where to "Shove it," sometimes the best way to tell them off is to tell them nothing at all. Confuse them by complimenting them. For example, "Your sunglasses are really cool." Choose wisely, because tolerance can be stylish too. Lastly, you may need to seek out some assistance from professionals. Consider getting a fresh perspective on the matter.