Despite having very little bottom dysphoria (compared to my intense dislike of the fatsacks on top of my pecs), my nightmares usually involve being out in public, and then suddenly realizing I'm in a night-shirt or something... with nothing covering my bottom half. Trying to hide or act like nothing's wrong, despite knowing people are going to figure out I'm a 'girl' if they look down there.
I guess I've gone most of my life ignoring and minimizing my chest... so the thought of people seeing it doesn't bother me. I'd be nervous if I found myself shirtless, but I've never had dreams about it.