There's a certain level of social wiggle-room we give kids. They don't quite know how the world works, so we give them a pass when they act out. What if adults, who are all about arbitrary social rules, acted as freely as their younger selves? Someone's about to throw a tantrum.
Now that you've seen adults acting like kids, why not flip it and reverse it? Watching these children behave like adults is amusing and cute, but sometimes you just wanna play on a slide without it turning into a philosophical discussion about free will, you know?