From Longman Dictionary of Contemporary Englishsmile/grin etc from ear to earsmile/grin etc from ear to earSMILEto show that you are very happy or pleased by smiling a lot She came out of his office, beaming from ear to ear. → ear
Examples from the Corpus
smile/grin etc from ear to ear• Father smiled from ear to ear, and he and I both ate like fiends.• Standing at the kitchen counter, shuffling his feet to the music, he caught himself smiling from ear to ear.• Randolph, smiling from ear to ear, quickly dressed into warm clothes and set out towards the toy factory.• He was grinning from ear to ear and pointing his finger up to the flies. 