For me, it’s sticking my hand out of the window of a moving car. Whether I’m driving or not, I love having the windows down and waving my hand in the wind. I’ve loved it since I was a child and I’ll never stop doing it!
Walking/balancing on curbs, retaining walls, downed trees in the forest - pretty much anything.
Me and my wife (no kids) have recently decided to do the ‘stuff you enjoyed being a kid’ type outings. Such as dino parks, castles, zoos, theme parks.
If you are an adult having kids is usually how you end up in those places and we decided just to do those things for ourselves.
Sandwich biscuits (like Oreo and the likes, but there are plenty local brands) are extremely popular among kids where I live. I still eat them, the same way as I did as a kid: split them in halves, eat the filling-less halves, and then join the halves with filling so I get to eat biscuits with 2x more filling.