Someone of simple intelligence or who once upon a time would be called a village idiot. Especially effective when teamed with the name of your next door town.
A person so stupid/idiotic and possibly a waste of space, a 'Ming Mong' is present throughout all societies. The local muppet who is proud of it deserves to be tagged a "Ming Mong". There are various ways in which the term can be used, as per the examples below: