put the bad mouth on

Meanings:

• 1.

  North AmericaUnited Statesinformalcolloquial
  • To speak ill of someone; to slander, disparage, or criticize another person behind their back.
  • To denigrate or bad-mouth someone to others, thereby damaging their reputation.

• 2.

  North AmericaUnited Statesregionalinformalcolloquialdialectal
  • To jinx or curse someone, i.e., to bring bad luck on a person by spoken words or superstitious action.