As kids, my brother and I would play that game where you put your forehead on the end of an upright baseball bat, go around it seven times and let the hilarity commence as we stumbled dizzily around the lawn. Then we'd do it again.
Now that I'm an adult, all I have to do is watch the kids spinning at the park, and I want to barf. They can whip around and around, laughing all the while, but I can't even do a cartwheel without being in the fetal position for 20 minutes afterward.
Luckily I'm not called upon to do cartwheels often, but still.
Also, might I say that nothing makes you feel cooler than commiserating with a bunch of other adults about how stuff you used to like now makes you nauseated. No more "all you can ride" bracelets at the fair for us; everything is too high or moves too much.
Meanwhile, I just have to avert my eyes when the kids get going... from the comfort of my stationary park bench.