You know, the guy above trying to be a smartass said there instead of their when referring to someone's idiocy. So really, the guy above is dumb as fuck.

A stupid person; it refers to the lack of surface area on an individual's brain. The general thought is that the more surface area (wrinkles, creases, etc.) a brain has, the smarter the person is. Conversely, a person with a smooth brain (no wrinkles) has less surface area and would therefore be stupid.

One of the only grammatical instances where the word "fuck" cannot be used. "Fuck" can serve as an adjective (your fuckin' stupid), verb (I want to fuck you), or a noun (you are one miserable fuck). However, when used as a noun, "fuck" is not plural by itself, like the words 'shit' or 'moose'. Fuck can only be plural when an 's' is attached (fucks). People still use it incorrectly though, showing there complete idiocy when they cannot correctly use the most versital word in the English language.