First created in Maine, this term mimics the drawl of the residents of that state (Summa for Summer) and refers to the affluent, cheerful, oblivious people who stream into an area of the country (often for summer vacation) and immediately alienate the locals with their disrespect,ignorance and conspicuous consumption.
"Ya know those Summa-shits who ask for foreign films at the Safeway and have loud drunken parties all night and tailgate the old aunties with their SUV on county line road...?
I drive REAL SLOW when they're behind me and smile REAL BIG when their faces pucker up and turn red."