Schlotterback, what a great name. 13 characters and everyone loves saying it. I've heard that "Schlotter", or some variation of that, means to shake or quiver in German. Check out the German word, schütteln, and hear it pronounced here, Google Translate. I've also heard that it somehow is translated to the family who baked bread by the muddy river, not exactly glamorous.
("Schütteln-back's in the United States)
But who's got the real proof of our family name? Give us links in our comments please!