Unsupervised propping

You'd think that with all my job-and-computer-free time, I could manage to supervise my child and not let him get injured. I swear I only left him propped on the couch for 5 seconds.... I turned back just in time to watch him land on his back on the floor. His cry wasn't a cry of pain but more of broken trust and "how could you fail me, mom?" Very sad. Truly. No more unsupervised propping for us. His abs are just too strong!