Freaky Friday <-- cliché?

My long-suffering wife is sometimes scared after I dash off one of my wild emails (the weirdest ones never get seen). "And I sleep with you?" she'll comment. On Wednesday, I made an innocent, snide comment about an article in Publisher's Weekly, and I finally ended up, a few email exchanges later, with my 25-word synopsis for a new novel that I almost feel obligated to write, because it'll hit all the correct high-selling genre groups in the article. I give you: INTERSTELLAR CHRISTIAN WARRIOR -- A classic thriller in which an alien cowboy, spreading the Christian message throughout the universe, is hunted by his vengeful love child with Talia Shire. There it is: classic, thriller, murder, revenge, love, christian, sci-fi, and western.
Critical reviews are already coming in..."Yo! Alien." - Sly Stallone
Where do ideas come from?