Check out this interesting documentary from the Discovery Channel: Star Trek The True Story.
-- Vice Admiral's log, stardate 57134.2
... I began to panic and asked my human companion of the meaning of toon. He replied that it was something that was not real. I protested to him that I was walking and running and killing. What did he mean that I was not real? He replied that everyone knew the universe was a computer simulation. Occasionally, he had to accompany another toon too.