The ending is reached on day 365, once your dream on that day is over, it will initialize a cutscene. Which displays a few different things, like the title of the game, LSD, some physcadelic transitions, a cucumber (For some reason).
And more, this ending has been discovered, and a video of it is available on Youtube at the link below:
http://www.youtube.com/watch?v=0U2LV7320zA
He shows his last dream, and then the last cutscene.