When someone simpers, they smile in a silly way, often because they want to please someone or they are being insincere.
Simpers can seem fake or not genuine, like someone is trying too hard to be liked.
Examples:
She simpers when she wants something from her parents.
He simpers at the teacher to try to get a better grade.
The clown simpers to make the children laugh.
The cat simpers at me when it wants food.
The villain simpers as he makes his evil plan.
The princess simpers at the prince to make him like her.