dirty laundry

Short definition from Wiktionary

Noun

1. 1
   Used other than figuratively or idiomatically: see dirty, laundry.
2. 2
   Unflattering or embarrassing facts, or questionable activities that one wants to remain secret, but which someone else may use as blackmail.
3. 3
   A clothes hamper or other container in which soiled laundry is placed.