Someone who is acting foolish (rebakah)

The first female to compare her stepfather to a pedophile was an original, the 378,612th was an imbecile.

When someone you know is acting beyond stupid. Dumb, unknowingly, stupid. Yeah, I know a lot of them.

A person with moderate to severe intellectual disability having a mental age of from three to seven years and generally being capable of some degree of communication and performance of simple tasks under supervision. The term belongs to a classification system no longer in use and is now considered offensive.