Trams. Half of the world is urbanised, but I don't think big portion of the world's cities have trams.
Asparagus is almost as big a hype here as I assume cherry trees are in Japan.
Kale is also a big thing here, but I think many folks have access to kale, so I'm not sure about this one. People sometimes gather with a handcart full of alcohol and music, going on a tour to a place where they eat Kale (Kohlfahrt).
Döner, obviously.
Bottle deposit explains more of a non-existence of bottle littering.