Hey! Tangerines symbolize yuri in Chinese! Don't go calling them sour! You bad yuri girl!
This time she did better, she said "sweet and sour" which is actually a common way to describe forbidden love or unrequited love.
That said, they really are rubbing the tangerines in our faces, huh? I wonder if they want to convey the message that this is obviously a yuri manhua or something.