cat that ate the canary

1.
United StatesUnited KingdomAustraliaCanadainformalidiomaticcolloquial
- A person who looks extremely pleased with themself, often in a smug or self-satisfied way, typically because of some perceived advantage, success, or secret knowledge.
- Used playfully or teasingly to describe someone who is basking in recent good fortune or showing excessive pride.
2.
United StatesUnited Kingdominformalhumorous
- A person who appears guilty or knowingly responsible for a mischievous or secretive act, displaying a furtive or triumphant expression as a result.

Examples: