In 16th to 19th century Europe and North America, the slop trade was the manufacture and sale of slop, cheap ready-made clothing that was made by slop-workers and sold in slop-shops by slop-sellers.
I am finding out that kids LOVE it (hate it) when you confidently misundetstand their costumes. I have successfully convinced a handful of different trick-or-treaters I have never heard of the character Mario but they look like "a red version of Luigi, from those Mario games"