"Bätschi" seems to be a quite popular word in German politics nowadays, being popularized by the proposed new SPD head, Andrea Nahles. But I haven't been able to find a suitable explanation online, maybe because its popularity is too recent. Germans seem to find its meaning quite self-evident, and all the political talkshows or programs that I've seen just simply don't explain it.
What does "Bätschi" mean, exactly? And where did it come from?