If only i didn't know the episodes so well, that one is the sleep deprivation episode where aliens are dragging them into another dimension and performing experiments on them, the cat from Alien is spliced in there.
My favourite YouTube clip isn't suitable for a family site such as home theater forum. ;)
Let me post this instead. The black cat on the treadmill looks like mine only a bit fatter, no doubt why it's on the treadmill.