air your dirty laundry (in public)

「人に言うべきでないプライベートな問題を人前で語る」。ベランダで洗濯物を干す日本的にはそれが何か、という感じですが。

Truuconfessions: Say the Inappropriate Things You Can’t Tweet About on Mashable

With truuconfessions, you can anonymously air your dirty laundry in different categories like home, office, or body, mark updates you can relate to with the “metoo” button, favorite confessions, and leave comments.

metoo button means "me too".