Trick-or-Treat

Sue Grafton, 'F' Is for Fugitive (1989; rpt. New York: Bantam Books, 1990), p. 204:

I have a friend named Leo who became phobic about old ladies after one wrapped a turd in waxed paper and put it in his trick-or-treat bag. He was twelve at the time and said that aside from spoiling Halloween for him, it ruined all his candy corn. He never could trust old folks after that.

Hat tip: Mrs. Turdman.