I came across a sentence as follows.
Most teachers attest to the superior intelligence Ralph has displayed. Because of this, one of the teachers wants to register him in a local quiz show. When he is asked about it, Ralph exclaims, “Boy, would I!” Everyone is excited about the big quiz show.
Ralph is not making a question, nor is he making a negative statement or anything that would justify inverting the word order as far as I know.
I would like to know why the person responded using subject-auxiliary inversion?