I've only seen stuff thats not there once, I was camping with a couple of mates and its the most I've smoked in one sitting, like 8 whole J's.... One of my mates started writing on the floor of the tent (which was hotboxed by now), and I really did think there was some sort of small animal running around the tent, omg I nearly freaked out. It was a great night tho, when we calmed down we went onto a construction site near the campsite and climed on one of the diggers, stupid thing to do I know, but it was alright, we just had fun chasing each other around the site. Omg, what a good night....