If you listen to the audio plays: What's your favourite episode? What's your favourite type of episode? (For example I really like the ones that start with some sort of spooky supernatural creature sighting) Have you read any of the books? Have you listened to all of the episodes that are currently out? Have you listened to the kids version?
(btw sorry if reading this in english feels weird I know it's a german series but I wanted to not make this totally confusing for someone who doesn't speak german if you want to respond in german that's cool too)