Stand by! Here comes another piece of totally useless information guaranteed to bring any dinner-party conversation to a shuddering halt. Did you know that ...
... the expression 'blowing hot and cold' emanates from the Ionian philosopher, Anaximenes (late 6th c. BC), who asked the sort of daft question only philosophers can dream up and then worry about it for a lifetime, to wit: How can a man blow hot and cold air. His answer was that it depended on whether you opened your mouth wide or kept it nearly closed.
Go on, you try it; it's true! According to Prof. R. G. Collingwood*, this "is an experiment of the utmost importance for cosmology". If you want to know why, you will have to buy his long out of date book. A couple of my young readers have recently got married so if their spouses complain in the future (and they will, oh yes, they definitely will) and accuse them of 'blowing hot and cold' they will be able to stun them into silence with an explanation of that phrase. (During that moment of baffled silence, quickly take advantage and slip out to the pub - take the advice of a veteran in these matters!)
* The Idea of Nature by R. G. Collingwood, OUP, 1965