What the heck? Is it the act of picking the stuff up--er, that is, the looking till you find something you want? Or is it, um, an adjective or a noun for the stuff itself? Do you say, for ex., "I went mongoing"? Or, "I picked up a fine piece of mongo today"? Or maybe, "That couch was mongo"--meaning you got it free off the street, and brought it home?
Is there really all that kind of stuff sitting around on the sidewalks of NYC? Constantly?