The idiomatic expression "couldn't hit a barn door" is a colorful and humorous way of conveying one's poor marksmanship or inaccuracy.

Tracing its origins, this phrase first emerged in the late 19th century, evolving from earlier variations like "couldn't hit a haystack" or "couldn't hit a house."

The core idea behind this idiom is simple - a barn, being a large and imposing structure, should be an easy target to hit.

Yet, the person being described is so unskilled with a firearm that they would somehow miss even such a sizable mark.

This immediately conjures up a comical mental image, poking fun at the individual's lack of precision and coordination. - https://farmhousebarns.com/blog/couldnt-hit-a-barn-door-meaning/?unique_id_726dc7hc

"The Enigmatic Idiom: Delving into the Origins of 'Couldn't Hit a Barn Door'"