Imagine...

...you are a clinician in a friendly neighborhood where 17 teams of retired people (over 60) meet regularly in parks to get exercise and some social time by practicing tai chi routines to music (and sword dances, and fan dances, and more). You've brought some visiting foreigners (rarely seen Americans) to watch the practice, to show how your society finds a wonderful way to encourage older folks to exercise. This is the sort of activity you yourself enjoy, and are quite adept at. It's a sunny afternoon, and everyone is feeling lighthearted. The spirit moves you to join in the practice. So you do.

That's the sort of thing that happens in Tianjin, China, where people don't seem too terribly inhibited... which is a lovely thing, in this case. (Watch sword dance video below.)