Absurd -

Arthur lived in a town where the rain only fell upward and the clocks ran backwards on Tuesdays. One morning, he woke up to find that his reflection in the mirror had decided to quit and was currently packing a tiny suitcase.

Arthur didn’t find this particularly strange. After all, his neighbor, Mrs. Gable, had recently replaced her front door with a large block of blue cheese. Instead of questioning the physics of a departing reflection, Arthur simply asked if it needed a snack for the road.

What's the best, most absurd premise you've seen in a fantasy story?

"I’m tired of the routine," the reflection said, its voice sounding like a muffled radio. "I’m going to become a professional cloud-counter in the next dimension."