"the most culturally appropriated culture is AMERICAN culture"

You should check out Japanese Bosozoku or Yanki cultures, where they appropriated 1960s Brit Rocker Culture and 1950s US car culture, respectively, and added unique Japanese twists. Instead of café racers, the Bosozoku have 1970s style bikes with gorilla bars and all sorts of flamboyant colours, and the Yanki have 2' high pompadours or spiked hair. It's totally surreal.

Jeans are a great example.  From starting in the western US as riveted work pants to around the world in a century.  You don't get more appropriated than that!