The Answer Is: "BACK! BACK!"

What is...
What you don't want to hear your son happily yell right before you suspect something and turn around and see your son about to do a reverse belly flop (remember that 'team-building exercise' where you stand in front of someone and are supposed to just fall back and trust that they catch you? Exactly). Off of the couch. With no other team members in sight.

Wow. At least he had the sense to scatter a few pillows on the floor beneath him. Still, I think the re-entry would have been a doosy. Glad he was excited enough about his trick that he had to announce it first.