My son was describing Pittsburgh and uttered this malaphor. It is a combo of “small market” (sports term for a team that struggles to compete financially with teams from larger markets) and ” blue collar” (working class or having to do with manual labor). “Black market” (business of buying or selling illegal goods) may also be in the mix, confusing blue and black. Perhaps this phrase will catch on and describe those cities that are both small market and blue collar (Cleveland, Buffalo, Detroit, etc). Thanks to Kevin Hatfield for passing this one along!