the cat that ate the canary
Someone who is smugly pleased or self-satisfied. After her promotion, Janet spent the rest of the day looking like the cat that ate the canary. Look at those kids with their ice creams—the cats that ate the canaries!
the cat that ate the canary
Happy, often in a selfsatisfied way. Someone who was very pleased—and often smug—was compared to a house cat that figured out a way to liberate a pet bird from its cage and enjoy the aftermath.