Hair box (n)- Female genitalia, specifically the labia majora. Analogous to “fur burger” or “beaver”. A term generally applied to the private regions of the female anatomy but often with regards to a particularly strong presence of pubic hair.
A derogatory metaphor used to insult someone's intelligence level and comprehension of common sense, comparing their IQ to that of a box of hair, which--all things equal--should have an IQ of zero.