I am allergic to stupid people. Myself included.

While in a conversation on the matter, I realized that my way of making this obvious is not the best one.
What I do is to politely let the stupid people know they are being stupid.

While it yields results quickly, it counts for nothing in the long run. The stupid only pretend to understand, and they forget their mistake the second I exit the scene. Because I’m only being funny, and that gets the message across, but it does not always make it stick.

I will hereafter try to leave a deeper mark, make a snarkier comment when someone proves their inability to think.
I think dumb-ass and dumb-tits should do for starters. For the Romanian version, see the inspirational post by Mircea Popescu. You can read this post from ily’s blog to see how stupid people can affect us if left unattended.

Oh, right. You get bonus points if you’re also pig-headed!