Cantonese. What do you mean his wife is a sister-in-law in vernacular?

This sentence is a Cantonese proverb: "His wife is a sister-in-law", which is translated in Mandarin as "His girlfriend is a sister-in-law".

In Cantonese, "dancing girl" means "girlfriend" or "lover", while "sister-in-law" means "sister-in-law", so this sentence means that his girlfriend is actually his sister-in-law.

It should be noted that this sentence is a proverb, which is usually used to describe some special relationships, such as love relationship or marriage relationship between close relatives. In daily life, we should avoid using such language to hurt others.