Mungo

A Mungo is what the children in Little Lamplight refer to adults, since the time they we rejected by the inhabitants of Vault 87 telling them that they're already dead hence setting a grudge on all the residents of Vault 87 and all adults alike.

Origin
Possibly taken from the Mungo Man, an early human inhabitant of the continent of Australia, who is believed to have lived about 40,000 years ago. His remains were discovered at Lake Mungo, New South Wales in 1974. The remains are the oldest anatomically modern human remains found in Australia to date.