Curls one's lip is an expression that refers to an action where a person curls their lips upwards in a sneering or contemptuous manner. Some antonyms for this expression would be to smile, grin, or show enjoyment. These actions represent the opposite of curling one's lip, signifying a positive or happy emotion rather than a negative one. Other antonyms could include expressions of neutrality or indifference, such as remaining poker-faced or showing no reaction at all. While one may curl their lip in response to a displeasing or unfavorable situation, employing antonyms such as smiling or remaining neutral can help to create a more positive and welcoming atmosphere.