Dry wine is Minnan dialect, and "dry wine" means empty bottles and empty wine bottles. In Minnan language, "If … nothing" means "Yes …", which means "Do you have any bottles to sell?" This is called by the garbage collector.
People who buy abandoned empty wine bottles in Minnan and Taiwan Province provinces and then sell them to waste recycling stations to earn a little money are walking up and down the street, shouting "Don't sell the wine when it's dry". If anyone has empty bottles to sell at home, they will stop waste buyers.
The song "Dry wine is not for sale" is in Minnan language, but there are two typos. There are many elements of ancient Chinese in Minnan dialect. If you don't know ancient Chinese, many words can't be written at all. For example, the words "gan" and "if" in the title of the song are typos, and the correct word "gan" should be "ge", which appeared in Sima Qian's Historical Records 2000 years ago, meaning "wine bottle". "If" should be "when", which is used in Nineteen Ancient Poems. Because many people don't understand it, it is transliterated as "dry" and "if".