A makeshift home for a hobo, not a homeless person. Often very hard to spot by the eyes of a human, but for a hobo it is easy to spot. Multiple hobos may try to share one large nest, but hobos are very possesive, so they will often take a piss on each others stuff to claim it, which results in the hobos splitting up.
Guy 1: is that some sort ofclubhouse.
Guy 2: no dude some hobo needed a place to keep his shopping cart so he made a nest.