They’re still in Japan …
The country is so homogeneous, so unified in its history and culture, that most zingers don’t need set-ups at all. There’s no need for explanation or detailed backstories. Folks get right to the punch line. One common joke, about an Olympic gymnast whose leotard was too high, has apparently become so familiar that even the punch line isn’t necessary. All you have to do is gesture to your upper thigh.
I suppose we have a little bit of that, like when someone tells a story about some stupid incident. We might shorthand it and say, “Was this person blond?” Or perhaps quote a movie line that sums up a more detailed response. But my mother and my kids, for example, rarely see the same movies.
I can’t think of any other way a joke might work with all swaths of Americans. Can you?