British slang, 1960s—‘to disappear up one’s own arse’: to become self-involved, pretentious or conceited—‘to be up one’s own arse’: to be self-involved, pretentious or conceited
literally: constant variety or interest (originally with reference to theatrical performances; USA, 1879)—ironically: constant variety of troubles, difficulties, etc. (in Three Men in a Boat (1889), by British author Jerome K. Jerome)
a moment of sudden discovery, inspiration or insight—1918—from the reputed exclamation of Archimedes when he realised that the volume of a solid could be calculated by measuring the water displaced when it was immersed
‘to have a fancy for’—UK, 1900—loan translation from French ‘avoir un béguin pour’—French ‘béguin’ is from ‘s’embéguiner de’, meaning ‘to put on a bonnet’, hence ‘to put a sudden capricious idea into one’s head’
USA, 1900: to get a stage act ready—Canada, 1961: to organise oneself to undertake or achieve something—from ‘to get together’ (i.e., to organise, put in order, harmonise)
Canada, 1928—resembling Jeeves, the perfect valet in stories by the English author Pelham Grenville Wodehouse (1881-1975); this fictional character first appeared in 1915