Mother's boy, also mummy's boy or mama's boy, is a term for a man who is excessively attached to his mother at an age when men are expected to be independent (e.g. live on their own, be economically independent).
Mother’s boy（或者mummy’s boy、mama’s boy）就是我们俗称的“奶嘴男”，指到了应该独立生活的年纪还对母亲过度依赖的男人。
Being mother-bonded is sometimes seen as a sign of weakness, and has a social stigma attached to it in many places, although in other places it may be more acceptable or perceived as normal. A mother-bonded man is seen to give control of his own life to his mother, in exchange for a sense of security.
Alternatively, in recent years, some have begun using the term in a milder sense, merely meaning a man who is emotionally attached to his mother. Though this sense of the phrase is still uncommon compared to the original pejorative intent, mothers in particular may state their pride in their "mama's boy" sons.