fancy dress party

See fancy dress party for a costumed gathering. The Fancy Dress Party was a political party in England. They were formed in 1979 as a frivolous alternative to the mainstream electoral parties, and can be seen as a forerunner of the more prominent Official Monster Raving Loony Party. Their most famous policy was to use a smaller font size to automatically reduce the unemployment statistics.
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A costume party (American English) or a fancy dress party (British English), mainly in contemporary Western culture, is a type of party where guests dress up in a costume.
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