If you are one of the few who haven’t seen Inception, then first where have you been? And second don’t read the spoiler filled link above. Basically a totem is a device which allows the owner to decide if they are in the real world or a dream world. Your not meant to allow anyone to touch or play with your totem, because obviously that would then allow someone to craft another one in there mind. In short Totem’s are a…
"elegent solution for keeping track of reality…"
Mal came up with the idea out of necessity to help differentiate between the dream world and the real world. To that end, there were several rules to be observed with the totems – never let someone else handle your totem so as to keep them from controlling your perspective of reality by duplicating your totem perfectly. The totem was also to be something small and intimate to you for reasons of portability.
My massive spinning top is maybe a little over kill for a totem, but heck its all good fun, and its a talking point for those who have seen the film inception.