Discussion Forum—A Way with Words, a fun radio show and podcast about language

I've never heard that one.   I'd have thought that "so don't I" meant not "me too" but "me neither".   Are you saying they use it not negatively but positively?   Like this:

1) "I think we need more snow this year."   "So don't I."  ["me, too"]

2) "I don't think we need more snow this year."   "So don't I."   ["me, neither"]

Which way do they use it?

I moved from New York City to New Hampshire years ago and this phrase still causes a brain spasm when I hear it. It seems to be fairly local to the Merrimack Valley - Southern NH and Northeastern Mass. The natives don't bat an eye either hearing it or using it.