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.
Related Idioms and Phrases :
look as if butter would not melt in your mouth
appear deceptively gentle or innocent – informal
the butterfly effect
the phenomenon whereby a minute localized change in a complex system can have large effects elsewhere
The expression comes from chaos theory. In 1979, Edward N. Lorenz gave a paper to the American Association for the Advancement of Science entitled … Does the flap of a butterfly's wings in Brazil set off a tornado in Texas?
have butterflies in your stomach
have a queasy feeling because you are nervous – Informal
button your lip
remain silent – informal
on the button
exactly right - informal chiefly US
press the button
initiate an action or train of events - informal
During the cold war period, this expression was often used with reference to the possible action of the US or Soviet presidents in starting a nuclear war.
push his buttons = press his buttons
be successful in arousing or provoking a reaction in someone - informal
buy the farm
die - North American informal
This expression originated as US military slang, probably with the meaning that the pilot (or owner) of a crashed plane owes money to the farmer whose property or land is damaged in the crash.
adopt tactics which delay an event temporarily so as to have longer to improve your own position
by and large
on the whole
Originally this phrase was used in a nautical context, describing the handling of a ship both to the wind and off it.
by the by = by the bye
let bygones be bygones
forgive and forget past offences or causes of conflict.