So I'm a pretty snarky person to start with. One of my big challenges when running Dark Heresy is to get the tone right. I want it to be dark -- the Warhammer 40K universe has plenty of horrific aspects. I also want to maintain the dry sense of humor that's characteristic of the source material. Since I have a tendency to go for the easy joke, I sometimes/often slip over the edge and wind up making my own jokes about the setting, which sort of gives players permission to laugh rather than dread. And to me, the dread is important.
What's a good way to maintain tone in a Dark Heresy (or Rogue Trader, or even any of the Warhammer Fantasy games) campaign? How can you keep the game from going too far over the top, given that it's such an over the top setting to start with?