Cute Young Brunette Girl With Long Hair And Blue Eyes Reveals Her White Hat And Slip In The Barn With A Hay

"He couldn't hit the broad side of a barn" is a popular expression for a person having poor aim when throwing an object or when shooting at something.
To "lock the barn door after the horse has bolted" implies that one has solved a problem too late to prevent it.
"Were you raised in a barn?" is an accusation used differently in various parts of the English-speaking world, but most commonly as a reprimand when someone exhibits poor manners by either using ill-mannered language (particularly if related to manure), or leaving doors open.
"Your barn door is open" is used as a euphemism to remind someone to zip the fly of their trousers.