At warp speeds no one needs to poop. And no one can hear you scream, either. See, it's Einsteinian. When you go that fast you're left hanging, so to speak, and the red-green shift effect kicks in and, well, there's a lot of esoteric math and shit that happens. It's like when you watch a train go by and your train is going faster the other way and you're using the train's toilet. It gets all relativistic. The answer, in the end, is "Where do you think all of that dark matter came from?"