The term mamas boy is often used as slang to describe a man who has an unhealthy dependence on his mother well into adulthood when he is expected to be independent and self-reliant.

What is wrong with being a mamas boy?

Being a mamas boy does have its disadvantages. Mamas boys are less likely to decide who he wants to marry because he must have the approval of his mom first, so basically: his mom is his wife. They grow up needing their mom to take care of their problems and have no way to handle stressful situations themselves.