From Longman Dictionary of Contemporary Englishsmack your lipssmack your lipsHBHHUNGRY/STARVINGto make a short loud noise with your lips before or after you eat or drink something to show that it is good He drained his glass and smacked his lips appreciatively. → smack
Examples from the Corpus
smack your lips• Cranston snored gently like a child, muttering now and again and smacking his lips.• Shove his face into his own shit, they were learning, and he will devour it, smacking his lips.• The young one smacked his lips.• He smacked his lips and stroked his moustache with surprise.• She begins cackling, smacking her lips, like a child thinking of a turkey dinner.• Granny Weatherwax smacked her lips, like some one emerging from a very deep sleep.• The woman seemed to be smacking her lips over every word.• The chimpanzee then pulls out the grass stem and picks off the termites with its teeth, smacking its lips with pleasure. 