The phrase "I'm not crying, you're crying" is an expression often used in a lighthearted or joking manner to convey emotional sentiment. It typically occurs when someone becomes deeply moved, touched, or emotional about something, such as a heartwarming or poignant moment in a movie, a touching story, an act of kindness, or any situation that evokes strong emotions.
By saying "I'm not crying," the person is playfully denying their own emotional response, implying that they are not the one who is affected by the situation. Then, they follow it up with "you're crying," suggesting that the other person or people present are the ones who are emotionally moved, even though they may not want to admit it.
It's often used as a way to share a collective emotional experience and to connect with others over a shared sentiment. Overall, the phrase is light-hearted and humorous, and it acknowledges the power of emotions and the shared human experience.