Re corn dogs: My husband loves them! We even planned a trip down Route 66 (what's left of it, that is) to include a classic old diner/cafe on the outskirts of Springfield, IL, that has specialized in them for ages.
I've seen a place in Berlin that has them, but, since it was pouring and the one person in the food truck/trailer was busy with a large phone-in order and wouldn't serve us, we didn't order any and went on.
There's a small outdoor market on Greifswalder Str., a block or two outside of the Ringbahn, a bit past the EDEKA. The market is in front of a long high-rise block of offices and apartments. The trailer, closer to the street than the rest of the market, had a variety of types of fast food, but corn dogs were one of them. I think you could choose what type of sausage went into it. I only get there every couple of years, so I'm not sure that it's there.
My husband can't figure out why they are available more often here, such as at street festivals.