Also Can Be Phrased:
air your dirty laundry in public.
To talk about things (usually a problem or dispute) that should be kept private.
To air your dirty laundry means to talk about private issues amongst others that are not involved. It originates from the fact that your dirty laundry (an analogy for dirty secrets) should be kept out of sight when people are visiting, otherwise it could be embarrassing for you or them. It can also be phrased "Don't air you dirty laundry in public".
"I didn't mention the fact that my sister is violent and has been in drug rehab twice because I didn't see any reason to air our family's dirty laundry."
"If Nancy would stop nagging me so much, I might be more inclined to help around the house." ... "John, don't air you and your wife's dirty laundry. We don't want to hear it."