Well, it's hard to draw a direct analogy, but it's something like this. Imagine that you're reading some sci-fi or fantasy loosely based on UK, and all characters are basically this guy:Even if there's a danger of belaboring the point, but what I originally wanted to say is that grimdark and funny are not mutually exclusive, even without resorting childish jokes - although I don't quite understand what you just wrote .Well, it depends. Reading about Kislev for a slav is a quite funny experience, Chaos incursions notwithstanding. Kvas and droyashka, atamanka, boyar, Raspotitsa and ВЧК. After all this shit all grimness is kinda replaced by razvesistaya klyukva. Vostroya at least wasn't so prominently used in WH40k and it was more interesting visually.Obviously you are correct here and I shouldn't have lumped all of DnD together for my example, but I just wanted a quick and dirty comparison - FR or Dragonlance vs. KislevAD&D had it's share of grimdark worlds, both in horror and survival main themes - Dark Sun, Ravenloft, also many parts of Planescape were pretty damn grim.
Only they are played almost completely straight, without hints of irony. Oh, and the characters are a mix of English, Scottish and Irish stereotypes without any distinction between them.
It can be funny, but it seriously lessens the grimdark concentration.