Originally posted by Gunslinger 
I honestly don't get it   
 
 "Carpetbagger" is a traditionally derogatory term for a northerner in use since (I believe) Reconstruction.  It stems, basically, from northerners who would move down south with nothing but "what they could carry in a carpet bag" to do all sorts of obviously evil deeds, I suppose.
As for the double meaning, well, Gunslinger, I'd say if you don't get it, you're probably a gentleman 
