Chapter Mercia to Merry Dun of Dover of M by Brewer's Phrase & Fable

Merry Andrew So called from Andrew Borde, physician to Henry VIII., etc. To vast learning he added great eccentricity, and in order to instruct the people used to address them at fairs and other crowded places in a very ad captandum way. Those who imitated his wit and drollery, though they possessed not his genius, were called Merry Andrews, a term now signifying a clown or buffoon. Andrew Borde Latinised his name into Andreas Perforatus. (1500-1549.) Prior has a poem on “Merry Andrew.”
    The above is the usual explanation given of this phrase; but Andrew is a common name in old plays for a varlet or manservant, as Abigail is for a waiting gentlewoman.

Merry Dancers The northern lights, so called from their undulatory motion. The French, also call them chevres dansantes (dancing goats).

Merry Dun of Dover A large mythical ship, which knocked down Calais steeple in passing through the Straits of Dover, and the pennant, at the same time, swept a flock of sheep off Dover cliffs into the sea. The masts were so lofty that a boy who ascended them would grow grey before he could reach deck again. (Scandinavian mythology.)