In British and Irish folklore, seeing a lone magpie is traditionally said to bring bad luck.
The belief is remembered through the counting rhyme “One for sorrow, two for joy.” Its exact lines vary, but the basic pattern assigns different meanings to the number of magpies seen together. One bird is associated with sorrow, while pairs and larger groups receive more favorable interpretations in many versions.
Magpies are intelligent, conspicuous birds, so their social behavior may have helped make sightings memorable. The rhyme turned an unpredictable encounter into a simple counting system that children could remember and repeat. It is folklore, not a reliable prediction of events.
The superstition is especially established in Britain and Ireland, but meanings differ elsewhere. In some cultures, magpies are linked with good fortune, cleverness, or even positive news. The famous rhyme should therefore not be treated as a universal belief about the species.