Such was the case in our house when we first moved in. Under the kitchen sink was a hole. This hole was mostly covered by a big rock. Note use of the word mostly.
A little further explanation of the old kitchen (now remodeled without really big rock or hole) - the cabinets were a U-shaped configuration, but between them were no barriers, so behind the cabinet doors it was just one long continuous space. Enter the demon opossum.
I'm in the back when I hear a blood-curdling scream. I run to the kitchen. My significant other is babbling incoherently and pointing at the silverware drawer (which is shut). Tentatively, I reach forward and pull it open (cue sinister music), when:
Two of us were then screaming incoherently and babbling at the silverware drawer. The demon opossum took one look and hightailed back around the cabinet U and out of the hole through which he came.
Moral of the story: Make sure you get a big enough rock for the job!
Any close calls with wildlife in your house?