Yup, they do.

In the middle of the night, I occasionally hear the unmistakable thump of feline bodies tumbling over each other in combat -- mock combat, without growling, hissing or yowls. Both cats like to lounge on the runner at the top of the stairs, in front of the bathroom door, where they can do the most damage to a sleepy person stumbling around in the dark. The runner in question is dark red, and the cats are black. Their camouflage technique is excellent.