shoot oneself in the foot
Foolishly harm one's own cause, as in He really shot himself in the foot, telling the interviewer all about the others who were applying for the job he wanted. This colloquial term alludes to an accidental shooting as opposed to a deliberate one done so as to avoid military service.
Words nearby shoot oneself in the foot
shoot down,
shoot for,
shoot from the hip,
shoot off one's mouth,
shoot one's bolt,
shoot oneself in the foot,
shoot out,
shoot straight,
shoot the breeze,
shoot the works,
shoot through