Something under the bed is running around squeaking

The running: gambolling, cat-like footsteps; gleeful.

The squeaking: high-pitched, staccato bursts piercing the dark; terrified.

“Kill it. Kill it. Kill it. Hobbes, I WILL GET OUT OF BED AND DO IT MYSELF.”

Irony: a mouse that is not being tortured by a cat is quiet as, well, as a mouse.