devil's dust

/D EH1 V AH0 L EH0 S D AH0 S T/
noun
  1. 1

    (slang, informal) Any type of powder or dustlike substance whose use or effect is considered to be harmful or malevolent.

  2. 2

    (obsolete) Shoddy produced by a devil (machine for tearing or cutting rags, cotton, etc).