a person or thing, initially ugly or unpromising, that changes into something beautiful or admirable—New Zealand, 1848—from Hans Christian Andersen’s story about a supposed ugly duckling that turns out to be a swan
absenteeism among police officers (and by extension other workers) who claim to be ill but are in fact absent to support union contract demands or negotiations—USA, 1967—alludes to the traditional colour of police uniforms
two different people or things are totally incompatible—1901—alludes to “East is East and West is West, and never the twain shall meet” in Ballad of East and West (1892), by Rudyard Kipling
1809—U.S. nautical, obsolete: the two-fathom mark on a sounding-line—Samuel Langhorne Clemens chose it as his pen-name in 1863, but a pilot named Isaiah Sellers had first used it as his pen-name
also ‘mustang court’ and ‘kangaroo inquest’—USA, 1840—a mock court that disregards or parodies existing principles of law; any tribunal in which judgment is rendered arbitrarily or unfairly
USA, 1792—to say to a person the things that they want to hear—allegedly from the story of a white man and an Indian who went hunting together, and killed a turkey and a buzzard
to vomit from drunkenness—U.S. students’ slang, 1980—likens the position of the hands of a person holding onto the sides of a toilet bowl while vomiting therein, to that of a bus driver’s hands holding the steering wheel
a person who shows no proficiency in the use of information technology—USA, 1998—from ‘techno-’ in ‘technological’ and ‘technology’, and ‘-saur’ in ‘dinosaur’, i.e., a person who is unable to adapt to change
USA, 2003—a group of people organised by means of the internet, mobile phones or other wireless devices, who assemble in public to perform a prearranged action together and then quickly disperse
USA 1813—a heavy metal ball secured by a chain to a person’s leg to prevent escape or as a punishment—figuratively, mid-19th century: anything seen as a heavy restraint, especially the matrimonial bonds