The reel thing.
The next time you're in a restaurant trying to order a second drink, wondering how all 18 wait staff can ignore your waving hand, raised voice, and distress flares- try flying a kite.
In my experience, the minute you unfurl a kite in any public space in Shanghai, a crowd of middle-aged Chinese men will immediately appear to proffer advice, show you how to hold the reel, tug the string and do all the donkey work by running 25 metres across the park with the damn thing.
Some of these people take the whole business far too seriously, I've seen grown men get into fistfights because their green nylon Eagle just crossed strings with another man-child's dubious looking Doraemon.
Yes I know they invented it, but I would just rather be allowed to crash my own kite into a tree then go home in tears without the locals watching my shameful descent. And seriously, can I get that second drink?

