What is the origin of that a curly question idiom?

The idiom "a curly question" doesn't have a specific, documented origin. It's likely that it arose organically from the common association of "curly" with something difficult or complex, possibly related to:

* Curly hair: Often seen as unruly and difficult to manage.

* Curly lines: In written language, a "curly" line might signify a twist or unexpected change in direction, making something more complicated to follow.

* Curly wood: Curly wood grain is intricate and difficult to work with.

Therefore, a "curly question" is simply a way of describing a question that is difficult to answer, perhaps requiring a lot of thought or explanation. It's likely the idiom evolved through everyday speech and became popular due to its descriptive and relatable nature.