The noun ‘wolf whistle’ appeared in the USA in 1943—Wolf-whistling was popularised by the wolf, a cartoon character created by Tex Avery in Little Red Walking Hood (1937), which reappeared in Red Hot Riding Hood (1943).
Classical Latin ‘muscŭlus’, literally ‘a little mouse’, also denoted ‘a muscle of the body’, especially of the upper arm, from the resemblance of a flexing muscle to the movements made by a mouse; ‘muscŭlus’ was also used in the sense of ‘mussel’.
First recorded in The Leeds Mercury (Leeds, Yorkshire) of Friday 26 August 1938, the phrase ‘to use one’s loaf’ means ‘to use one’s common sense’. Here, ‘loaf’, a shortening of ‘loaf of bread’, is rhyming slang for ‘head’.
‘handbag’: to bully or coerce by subjecting to a forthright verbal assault or criticism—originally used with reference to British Prime Minister Margaret Thatcher in The Economist (7 August 1982)—from literal meaning ‘to batter or assault with a handbag’
Of American-English origin, the colloquial phrase ‘hot under (or ‘in’) the collar’ means ‘extremely exasperated or angry’. The earliest instance that I have found is from The Chicago Tribune (Chicago, Illinois) of 8th July 1869.
U.S., 1876—‘bulldozers’: members or supporters of the Democratic Party who used threats and acts of violence in order to prevent Afro-Americans from voting for Republican candidates
Italian translation of Latin ‘in pectore’ (‘in the breast’, ‘in the secret of the heart’)—when a pope announces that he has appointed a cardinal whom he reserves ‘in petto’, it means that he will reveal this cardinal’s name later
Originally, the mother was the object of ‘deliver’, the image was of delivering (freeing) her from the burden of pregnancy. Nowadays, the healthcare provider or the mother is the subject, the image is of delivering (handing over) the baby, as if it were a package.
‘slipshod’: ‘characterised by a lack of care, thought or organisation’—formed after the obsolete noun ‘slip-shoe’ (= ‘a loosely fitting shoe or slipper’); ‘shod’ (meaning ‘wearing shoes’) is the past participle of the verb ‘shoe’
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