From wikipedia:
"A black comedy, or dark comedy, is a comic work that employs black humor, which, in its most basic definition, is humor that makes light of otherwise serious subject matter, or gallows humor."
Gallows humor:
"Gallows humor is humor in the face of or about very unpleasant, serious, or painful circumstances. Any humor that treats serious matters, such as death, war, disease, crime, etc., in a light, silly, or satirical fashion is considered gallows humor."
Moreover,
"The definition of black humor is problematic; it has been argued that it corresponds to the earlier concept of gallows humor."
So dark comedy is humor that makes light of something serious, like death. It doesn't have any strict definition, so you can use the term in a variety of ways.
That's all there is to it.
It's not impossible, nor does it sound like it.