There is a regional slang dialect in the region of Brno (South Moravia, close to Austrian border) called Hantec. Lexically it draws on German, Austrian German, Yiddish, Romish, and perhaps some other languages for all its quirks, some morphology follows the South Moravian dialects, but overall its grammar is based on Czech. Hantec (including its written form) is rather hard to comprehend to non-speakers. It seems to be slowly disappearing, although many lexical items persist and are used by the general population in the city (e.g., koc (a young woman) is supposed to mirror a typical Austrian pronunciation of Katze).
I wonder whether there are other such regional dialects
based (or based to a large extent) on German influenced by German in an analogous (i.e., mainly lexical) fashion.