They pack all their gear in a series of plastic bags of various sizes, to keep their luggage organised.
It is not easy to recognise a plastic bag rattler, until it is too late and you are actually sharing a room, usually a dormitory with them.
At this point you will discover they usually go to bed before dusk and get up before dawn. Like birds, they make the most noise possible at these times in some sort of territorial proof of their existence. Unike birds, whose song is usually beautiful, the plastic bag rattler, will simply announce their presence by rattling plastic bags and their contents, as loudly as they possibly can, determined to wake, not only the dead, but also the rest of the world.
Plastic bag rattlers are a selfish lot. They believe everyone should get up and going when they do. They forget that the owls of the dormitory organised themselves well enough prior to going out on their nocturnal adventures, not to wake anyone when they snuck into bed at midnight.
As an owl I only wish the plastic bag rattlers would be half as considerate to those of us who tend towards the nocturnal, rather than just the diurnal and bloody well stop rattling their bags at dawn!