live off the land

Formerly referring to there being an adequately-abundant supply of wild food and clean water in a certain area that a human could survive there for extended periods, it nowadays is often a "grim grinds" reference to how wasteful the population in a given area is as a whole, and that a good scrounger could literally find enough edibles and other basic essentials in the neighborhood's dumpsters and waste-piles to sustain himself quite comfortably.