With this small and beautifully crafted item you will not only drive amateurs crazy, but also all magicians. You borrow a cigarette which is put into a previously inspected tube. The cover is also closely inspected by a member of the audience, and the tube closed by means of the cover.
With a sharp cutter or a borrowed knife, a cut is made through a slot in the tube and thus quite clearly through the cigarette. The knife really goes right through the tube, the cigarette hasn't got a hope. But when you take the cover off, an undamaged cigarette falls from the tube. If you like, you can have someone from the audience repeat the trick immediately. But of course the inevitable happens, when this person tries the trick, two cigarette halves fall from the tube, much to the amusement of the rest of the audience.
As nothing has to be added or disposed of, nothing that can be pushed or slid along, and the item can be examined under a microscope (including the knife), this will madden everybody who is trying to figure out how the tube has been prepared. There is no preparation and still the trick works with all normal cigarettes as described.