What if you ask for them but kinda jokingly like you have no actual expectation of getting them. For example my next line I will ask for them.

Pass me secret documents.

Now, my question - did I just break the law? Or am I only breaking the law if someone responds with secret documents?

The law requires intent: "Whoever knowingly and willfully communicates"

https://www.law.cornell.edu/uscode/text/18/798

So it would be up to a prosecutor and jury to determine your state of mind.

I guess if you are given secrets documents and you accept them, open them, or redistribute them you are guilty.

If you just say "oh no sorry I don’t actually want your secret documents, that was just a joke" and move on, you are fine.

Thankfully I don't have to.