I remember hearing this expression "Bist du los?", but I don't really remember the context.
In my mind, the meaning was something like "Are you crazy?" with the hand-waving in front of the face, but again, I cannot provide a context. I've tried looking for it on the internet but couldn't find anything, and my understanding of German is pretty limited. It is possible I heard it wrong. Does anyone know whether it exists, and, if it does, what's it's meaning?
As additional information, I might have heard it from my late grandmother, so it could be part of a dialect. She was a native speaker who emigrated from Germany as a young teen. She grew up in Lower Saxony, specifically in the city of Vechta.