We have a shelf. This shelf...well, shelves various things. But the bottom level of the shelf is empty enough that there's room for it to be occupied.
It often is. Because we have a heater vent which blows the heat onto the shelf in that exact spot.
It had a resident, and she was soundly asleep (or so I thought) when I went to my room to grab my work stuff. I was in my room for less than thirty seconds--probably fifteen. And when I opened the door...
...CAT.
Right there, sitting next to the door, looking up at me.
When she had, as far as I could tell, been fast asleep as I had gone down the hallway.