她是柠檬会酸人心他是薄荷会凉人心
[tā shì níng méng huì suān rén xīn tā shì bó hé huì liáng rén xīn]
The names indicate the emotional impact a person might have on others: 'She is a lemon, bringing a bittersweet effect to people’s hearts; he is mint, leaving them with a cooling and refreshing but distant impression.' It uses lemon (sour) and mint (cooling) as metaphors for personality traits or emotions felt.