Green’s Dictionary of Slang

a stupid, dumb person; as adj., stupid.

1978		Devo ‘Mongoloid’ 🎵 Mongoloid he was a mongoloid / His friends were unaware / Mongoloid he was a mongoloid / Nobody even cared.
1997		Eble Campus Sl. Apr. 6: mongoloid – stupid; lacking in culture or refinement.
1997–2000		College Sl. Research Project (Cal. State Poly. Uni., Pomona) 🌐 Mongoloid {offensive} (noun) Illiterate person.
2001		J. Stahl Plainclothes Naked (2002) 30: ‘I thought he was a genius.’ ‘Was he?’ ‘Sometimes [...] Other times he was a total Mongoloid.’.
2008		J. Niven Kill Your Friends (2009) 6: The usual reflexive anger at the attempts at spelling my name [...] one mongoloid has even gone for ‘Stellarfix’.