Sweeping?

me and a few of my friends were ridin around one night smokin blunts and the driver pulls up to this car-wash to talk to his buds, while I'm in the back smoking a bowl I notice this sketchy old homeless guy lurking behind the car-wash spying on us, I don't really do anything and just keep smoking the bowl. Then one of my friends buds decides to match us so he hops in the back of the car and we take off, as I look out the back window I see the same hobo emerge from the darkness and start drinking the half empty mountain dew the guy had left behind, we pull into this parkinglot not too far from the car-wash and start rolling a blunt, I do a quick scan to make sure there aren't any cops around and I see the homeless guy riding up to us on what looked like a 5 year old girls bike, he came up to the drivers window and asked us if we were "sweeping", we just sat there like , he eventually left.

now I'm not 100% up-to-date on my stanky hobo slang, can anyone tell me what the fuck sweeping means