Weed-littering

We find these quite frequently in front of the building I work. In the evenings or at night people who want to smoke some joints take shelter under the small roof at the front door of the building I work. It's an industrial area so it wouldn't be my first guess to come al the way up there to smoke a joint. Especially since the nearest coffeeshop (you know a Dutch coffeeshop, where they don't sell coffee very often) is at least 3 km away.
Well at least they're not junks leaving needles