Never heard anyone say "mong" in my life until I came here. I'll just assume it's a European thing
Lacking in physical and cerebal ability. General retardation. Generally: a total spastic
Mong is short for 'mongoloid', which was originally an anachronistic term for a Down's Syndrome sufferer. The modern Mong however is a total fuckwit, who deserves nothing less than complete humiliation for their idiocy.
No I don't need you to help me with my supermarket trolley, you fucking mong