To be clumsy, usually momentarily, by dropping or failing to catch something. I dropped another plate! I guess I just have butterfingers today. Coach, don't put Jimmy in the outfield—he has butterfingers!
have (or be a) butterfingersbe unable to catch deftly or hold securely.
This phrase comes from the idea that hands covered with butter will be slippery, making holding on to anything difficult. There was also a dialect sense of ‘unable to handle anything hot’, as if your fingers were made of melting butter. Butterfingers! is often jeeringly shouted at someone who has failed to catch a ball in a game.