ring aring of roses, a pocketfull of posies, atishoo, atishoo, all fall down

Meaning

Verse from a nursery rhyme.

Origin

From the playground rhyme. Often reported as referring to the Black Death (the bubonic plague in mediaeval Europe). The plausible-sounding theory has it that the 'ring' is the ring or sores around the mouth of plague victims, who subsequently sneeze and fall down dead. In fact the rhyme doesn't appear in print until 1881, six centuries too late. It is stretching credibility to think that it lasted for that length of time in common playground use but was never recorded.

More likely to have originated during the 19th century ban on dancing in the UK and USA, and that the words are mostly playful nonesense.