Old mouth and old face means shameless in Yunnan dialect. This sentence is Wenshan dialect, a language in Yunnan dialect, and many people can't speak it now.

Yunnan dialect generally belongs to the northern dialect. Reclaiming farmland in Ming Dynasty played a decisive role in the formation of Chinese dialects in Yunnan. With the gradual enrichment of people's historical and cultural knowledge, it is finally understood that the formation of Yunnan dialect is closely related to the migration of Han nationality and the formation of today's ethnic pattern.