It's slang that means 'of very low quality', or just simply, 'very lame'. It is derogatory and can cause offense. 애미(or 에미) 없다 literally means someone doesn't have his or her mother. Less commonly, 애비 없다 is said as well.
애미(or 에미) is what parents-in-law call their daughter-in-law; a dialectal word, I assume. Traditionally, women took charge of educating their kids on how to behave in public, how to act towards others in the way that's socially accepted way. It's so unfair a phrase because the society and fathers are also responsible for educating the kids who don't have their mother.