Also, look like the cat that swallowed the canary. Appear smug and self-satisfied. For example, After she hit her third winning shot, Jeannie looked like the cat that ate the canary. [Second half of 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.