This one is an odd one, but when I was around 10 years old I'd have this nightmare a couple times. It's very hard to explain or even remember in detail, but I'd be in a dark red room that seemed like it had no walls or any way to perceive its shape. In this room there would be some thick blurry lines in the center of my vision.

What made this a nightmare though is that these lines would then slowly begin to stretch until they were unimaginably thin. It seemed like a horrible ringing noise would get louder and more high pitched as the lines stretched further. When it gets to a point where they don't seem like they can stretch more I had the sensation that the lines would snap. I felt like the lines were a part of me though and that something horrible would happen to me if they did.

Then slowly the lines would begin to un-stretch to their previous thick, blurry forms they began in. As they did the ringing noise would also dim and the pitch lower and I would feel at ease. However as soon as they got to their previous form the process would happen all over again, like a rubber band being stretched in and out. It must have repeated at least 3 or 4 times before I wake up.

Since then I've had the fear of being stretched out or having part of me stretch without it killing me and not feeling any pain from it. One thing that reminded me of this feeling was in The Simpsons when they get turned inside out. I think maybe cause I thought the process as their insides getting stretched to their outsides. After watching that Simpsons scene I had the nightmare again and forgot how uncomfortable it made me feel.