noun a large cylindrical cup with a handle.
Brit. Informal a stupid or gullible person
ORIGIN probably Scandinavian.
Mug is a Scandinavian word meaning "drinking vessel". It was common in the 17th and 18th Centuries to decorate drinking mugs with grotesque caricatures of human faces, and "mug" became a popular slang term for "face". It also became a slang term for "guy" or "fellow", sometimes "a sucker" or "a fool" (although I have been unable to find any explanation of how mug actually came to mean stupid or gullible).J.K. Rowling has stated in interviews that she used the word ‘mug’, in the gullible sense of the word, for the basis of ‘muggles’ in the Harry Potter stories.
Mug is predominantly a London/Estuary slang word however it is widely used throughout the UK. Other forms of the word mug include:
a mug’s game Noun A foolish activity
eg: Betting on horse racing is a mug’s game.Also
• noun (pl. same or mugginses) Brit. informal a foolish and gullible person.
— ORIGIN perhaps a use of the surname Muggins, with allusion to MUG
Teacup Estuary Stupid, foolish
A play on the word Mug predominantly used by teenagers.