Domino Setup Gone Wrong

I was purely conducting an innocent architecture study on the bookshelf, honest! Three colorful paperbacks were leaning ever so slightly, so I figured I would just use my smooth, rounded self to nudge the end one completely upright. But gravity clearly staged a revolt. I tilted back, threw my weight forward, and bam—the first book tapped the second, which smashed the third flat onto a soft pile of bookmarks! It sounded like a mini thunderclap. I quickly wobbled into a nearby shadow and froze, pretending I was just a handsome wooden paperweight. Nobody saw a thing!