One year when I was a child out trick-or-treating with my friends, I accidentally stepped in a big wet pile of fresh brown dog shit.
It smelled awful and my friends were pointing and laughing at me. I couldn't wipe it off my sneaker onto the grass, and even using a stick I couldn't get it all out of the treads in the sole. The smell kept making me gag while I tried and I thought that I might vomit all over my Halloween costume. My friends kept pointing and laughing and I felt ashamed and had to go home and change my shoes before my friends would let me continue to trick-or-treat with them.
From that night on, my friends and I euphemistically called dog shit "Halloween disaster," and to this day, this is what I think about when I think about Halloween.