I'm not sure why you are combining grounding and humor in the way it appears you are; like the humor has to be about the traumatic experience, just because the grounding is to help with that? Humor is humor. If you laugh, that's good. Doesn't matter what you laugh at.

One can only really learn from experience; books are not "reality"/part of experience. I am thinking about Julia Roberts in "Runaway Bride" when she was accused of not knowing how she liked her eggs so cooked eggs every way known to woman and that was funny to me, even though the knowledge that she had not thought about, didn't know herself well enough to know how she liked her eggs was painful. I love imaginative, creative, humorous, curious, thoughtful responses to problems like that.

One can't know what will cause another pain and should not live one's life worrying too much about the other people living their lives; too me, it seems very much like worrying how the neighbor's grass is doing, is it green or not doing as well as mine. Yes, when I'm taking to an individual, one-on-one, I should be aware of their situation and not make fun of it, but I don't feel making fun of a problem is the same as humor.

There's no humor in post traumatic stress as you say but I think there can be humor (to me) in my relationship to post traumatic stress and I often use humor to help myself see things differently. Psychotics talking to themselves is not funny but I can laugh at myself talking to myself and I'm not worrying about psychotics being upset because I'm not talking about them! What is it C.S. Lewis said in his book The Great Divorce? that those in Heaven would ". . .not make a midden of the world’s garden for the sake of some who cannot abide the smell of roses."

Too humor is a very individual thing; what you find humorous might be different from what I find humorous. You might find this interesting and useful (I do):

http://shadow.ieor.berkeley.edu/humor/