Victor Xie, "Stupid" is not a quality that you possess, it is something that you do. Don't judge people by outward appearances or reputation, judge them by what they do. There are a number of expressions using the ___is as ___does formula. Stupid is as stupid does. Beauty is as beauty does. Evil is as evil does. Each is a variation of the same basic meaning. You can even invent your own! Handsome is as handsome does. A hero is as a hero does. Italki is as Italki does.

If someone does something stupid, they are stupid.