Dave sez: almost all idiomatic expressions are unintelligible when they are read literally.

This is seemingly true beyond the English language, as well.

In Brazil, when two adult males meet, one may ask the other: "O que é que há com seu peru?" This question is literally about the other fellow's turkey. It is colloquially about one part of the other fellow's anatomy. Its conversational meaning is "How are you?" Neither the literal nor the colloquial meaning get one all the way to understanding the expression.