From Japanese ‘taikun’, ‘tycoon’ was originally the title by which the shogun of Japan was described to foreigners. The current sense originated in the Japanese Embassy to the United States in 1860, not from the use of ‘tycoon’ as a nickname of Abraham Lincoln.
During the Cold War, especially in the context of a possible nuclear war, ‘better red than dead’ was used to warn against uncompromising opposition to communism, while ‘better dead than red’ was used to express unconditional opposition to communism.
‘Reds under the bed’ and variants denoted an exaggerated or obsessive fear of the presence and harmful influence of communist sympathisers in a particular society, institution, etc. The earliest instance that I have found is from the Chicago Tribune of 28th September 1924.
Of American-English origin, ‘gravy train’ is first recorded in 1899 with reference to sporting achievement, not to financial gain; it originated in the use of ‘gravy’ in the figurative sense of ‘advantage’, ‘benefit’, first recorded in 1845.
Often used in phrases such as ‘to jump on the bandwagon’, meaning to join the popular or apparently winning side, ‘bandwagon’ denotes a popular party, faction or cause that attracts growing support; its primary meaning is a wagon used for carrying the band in a parade.
A calque of German ‘blauer Montag’, ‘blue Monday’ originally denoted a Monday on which people chose not to work as a result of excessive indulgence over the course of the weekend. Under the influence of the adjective ‘blue’ in the sense ‘dismal’, it came to denote a Monday that is depressing or trying.
The phrase ‘to turn up one’s toes’, meaning ‘to die’, might have originated in the Irish-English phrase ‘to turn up one’s toes to the roots of the daisies’, first found in the passive form ‘with one’s toes turned up to the roots of the daisies’, meaning ‘lying dead’.
U.S.—‘to see the elephant’: to see life, the world or the sights, as of a large city, to gain knowledge by experience. But in 1842, the original meaning of ‘to see the elephant’ was ‘to get sick and tired of something’.
In British slang, the noun ‘piss-up’ denotes ‘a heavy drinking bout’, and the phrase ‘couldn’t organise a piss-up in a brewery’ and variants mean ‘is’, or ‘are’, or ‘am’, ‘incapable of organising the simplest event, task, etc.’—phrase first recorded in 1980.
Of American-English origin, the slang term fat cat denotes a wealthy, influential person, especially one who is a heavy contributor to a political party or campaign. The earliest occurrence that I have found is from an article published in The Sun (Baltimore, Maryland) of 1 November 1925.