If your smile is contorted with contempt or your upper lip curled with distaste and disdain, you're probably sneering. And you should stop, because it isn't nice.
Many things can elicit a sneer: a terrible red carpet outfit, a disgusting plate of food, a stupid joke told for the third time. But sneers aren't just meant to show disgust. They're mean-spirited, mocking and often downright snooty. So now that you know the definition of sneer inside and out, resist the temptation to sneer at those who don't!