番薯 as an insult

Question

In Cantonese, I've heard people use 番薯 as an insult to people or objects before, like calling a stupid person 大番薯 or calling a useless object 生番薯. Can someone whom speaks Cantonese enlighten me on why is 番薯 used as an insult. I never expect sweet potatoes to be synonymous with stupid or useless!

Answer 1

i suspected that it’s the influence of a comic called “old master q” (老夫子)

https://www.oldmasterq.com/

one of the main characters is named “big potato” (大蕃薯), a short, fat, and; stupid guy.

one might guess the rest, from such stereotype 😸

Answer 2

Searching 番薯 doesn't show any slang/insult-related result.

When I hear people say 成嚿蕃薯噉 (being dumb), I imagine 蕃薯 was food for poor people who couldn't afford rice. Due to the typical stereotype of rural farmers who were mostly poor, and the presumption of poor people were less intelligent, the term 蕃薯 was linked to dumbness by association with the poor

Also:

蕃薯 is dense and simple and it is commonplace item.

When people looking for a metaphor, commonplace items are the obvious choices, that's why we used 豬 to be a symbol for stupid, not because pigs are stupid but because the farmers saw pigs more often than any other animal. There are many immobile objects, but we use 成碌木 (like a pillar of wood) for the metaphor of 'inaction' because wood is commonplace item

In any case, the character 大蕃薯 in the Hong Kong comic Old Master-Q certainly popularized the use of 蕃薯噉 (like a sweet potato --> being dumb) as an insult