The act of dancing or jumping.--Daniel Fenning's Royal English Dictionary, 1775
Feast day of St. Vitus,
a patron of dancers and those suffering from Sydenham's chorea, an involuntary-movement disorder also known as St. Vitus's dance. George Wood's Vitalogy: Food Remedies for All Diseases (1896) offered the following observations about the disorder and its treatment: "This disease is characterized by convulsive movements of the limbs, occasioning ludicrous gesticulations, and arising from involuntary action of the muscles. It has wittily been termed 'insanity of the voluntary muscles.' Causes [are] fright, irritation from teething or worms, self-pollution, deranged uterine functions, hysteria and descent from nervous, hysterical women. ... The stammering and stuttering, local manifestations of St. Vitus's Dance, are frequently the result of seeing or imitating others having the same defect. The most important part of the treatment consists in the use of moral influences, especially when the disease does not occur from any appreciable cause. There must be removal from too sympathizing friends, the patient being placed under the care of a kind but firm guardian. He must be encouraged to ... walk on short stilts."
...and stick a banana in his ear.