A marijuana user who will go to great lengths to gather any and all remnants of leaves, stems, seeds, etc... from all pieces of paraphernalia, bottles, cases, etc... to get high until his/her dealer calls them back, which always holds enormous uncertainties.
Someone who doesnt smoke on a regular basis but they will steal, or scrounge, one of your cigarettes due to their 'social' or 'casual' smoking habits. You are normally liable to be scrounged from after these 'casual' smokers have had a beer or two.