twinkle

idiomatic phrase indicating someone is secretly amused, knowledgeable, or mischievous

describes a sparkle in the eyes that suggests a playful or teasing nature

describes a sparkle in the eyes that shows amusement

describes a sparkle in the eyes that suggests playful malice or mischief

a small, barely noticeable sparkle

used to specify what is twinkling or the quality it represents, e.g., 'a twinkle of mischief'

to observe a sparkle in someone's eyes

to become aware of a sparkle in someone's eyes

to see or notice a sparkle, especially one that is not obvious