Scary, wide-eyed, woman in a towel stampeding through the festival

They are called weirdo's, and there's actually coding that creates them. Some you'll see dressed in a bathing suit and a Lucidor mask. I know, because when I committed one Sim to raising in the smallest apartment in the Spice Market, I went into the code for that area and nixed them all (along with all the tourist outfits).