dirty linen / laundry

What is the origin of the idiom "dirty linen" and when to use it?

The idiom "dirty linen" is believed to have originated in the 19th century and has its roots in the idea of laundry. In the past, it was common for people to wash their clothes by hand and hang them outside to dry. This phrase is now used figuratively to describe the act of discussing private or embarrassing matters in public, especially those relating to personal relationships or family issues.