A common, seemingly contradictory expression used to emphasize that something is really bad or totally wrong. (In this context, bien functions as an intensifier similar to really).
My homework is BIEN MAL, that is why I got a zero.
A phrase used to indicate that something is going very poorly or is a total mess. (While mona literally means female monkey, in this context it refers to a situation that is failing or in a terrible state.)
Your dad told me the family business was going como la mona.