Explanation: it's because the girl's lips look more like a duck's beak than a mother duck's haha.
It's because the girl's lips resemble a duck's beak rather than a mother duck's, which creates a humorous comparison. This play on appearances suggests that her lips are shaped or puckered in a way that brings to mind the sharp or exaggerated look of a duck's beak rather than the soft, nurturing image typically associated with a mother duck. The added "haha" at the end emphasizes the lighthearted and playful nature of the observation, making it clear that it's meant to be a joke rather than a serious comment.
