I recently hopped over to Amazon for some reason or another, and was immediately presented with this prompt: 
There it was, a prompt for buying a book from an author I’d bought a couple books from before in the past.
“Oh,” I said to myself, “that’s dirty. That’s just dirty. That’s not playing fair.” And I continued saying that as I clicked on the title and pre-ordered the book. It was straight out of BJ Fogg’s behavior model — I had the motivation (“I like this author!”), I had the ability (It was two clicks between seeing this prompt and pre-ordering the book), and this provided the trigger. Well played, Amazon.