Wiktionary
puppy dog eyes
n. A facial expression showing credulous or unsophisticated innocence or naivety.
Usage examples of "puppy dog eyes".
With her hands and mind busy with a flood of customers, Morgana reminded herself that she would have no trouble handling a cocksure storyteller with puppy dog eyes.
Summer gazed into his puppy dog eyes and thought, No, I Hven't made a mistake.