Smells. The kryptonite is a toss up between two smells. One, colostomies, two, a blend of feces coupled with stinky, infected pressure sore at the coccyx. The latter, which I wasn't expecting, in my first year, was so bad, I had to step away because my mouth started watering and stomack started crapmping (which herald vomit about to happen). I didn't vomit, but had to get a mask with some scented something. That whole experience coupled with my first in-person experience with a cavernous wound, big enough to stuff a tennis ball into, was just too much for my young nurse senses to process.