"I once swapped the dental floss container of my girlfriend with my version I had prepared in advance (it helped that she was studying to become a dentist and that I knew she always had dental floss in her toilet bag when she came to visit me): * I bought dental floss of the same brand, * carefully opened it, * removed the thread inside, * wrote a long, personal letter, * cut it in long small pieces, * taped those pieces together to form a long paper string, * roled it up and * placed it inside the dental floss container. * [picture of the result](http://www.flickr.com/photos...) I can positively say she was very pleasantly surprised :)" - Jeroen Van Goey