The phrase ‘all behind, like a cow’s tail’ and its variants mean ‘left behind’ and ‘late in accomplishing a task’. They appeared in print in the mid-19th century in the USA, Australia and Britain.
UK, 1937, colloquial—‘to have done something more than oneself (or someone else) has had hot dinners’: used jocularly to emphasise the subject’s wide experience of a particular activity or phenomenon
mi-17th century—probably from ‘hand in (the) cap’, used of a sort of game in which players put forfeit money in a cap and then drew from it—later applied to a race between two horses (the better of which carried extra weight), arranged by such rules
The literal meaning of ‘rocket science’ (USA, 1930) is the science of rockets and rocket propulsion—in the 1980s, in connexion with sports, it came to be used ironically as a generic term for anything requiring a high level of intelligence or expertise.
A diminutive of ‘pūpa’ (‘a girl’, in transferred use also ‘a doll’), the Latin feminine noun ‘pūpilla’ came to also denote ‘the pupil of the eye’ on account of one’s own reflection seen when looking into somebody’s eye—the same metaphor underlies ‘to look babies in somebody’s eyes’.
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.
The 1776 French translation of Laurence Sterne’s ‘The Life and Opinions of Tristram Shandy’ gave to French ‘dada’, a child’s noun for ‘horse’, the figurative meaning of ‘favourite pastime’ or ‘pet idea’.
‘baloney’ or ‘boloney’: ‘humbug’ and ‘nonsense’—USA, 1922—American-English alteration of ‘bologna (sausage)’, a large smoked sausage made of seasoned mixed meats, from the name of Bologna, a city in northern Italy, where these sausages were first made
‘queen’s’, or ‘king’s’, ‘cushion’: a seat made by two people who cross arms and hold each other’s hands to form a support for another person—Scotland and northern England, 19th century
UK, early 19th century—an imaginary street where people in difficulties, now especially financial ones, are supposed to reside—urban counterpart of ‘Dicky’s meadow’