The setup: pull the cellophane halfway off the cigarette box and use a lit cigarette to melt a hole in the center.
Next, tear off just the filter of another cigarette and drop it inside the hole. The filter should rattle around freely inside.
The challenge: without manipulating the cellophane, get the filter out.
The solution: if you put a little bend in the box itself, you can blow right into the cellophane and the filter should fly right out!