E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Fast and Loose (To play).
To run with the hare and hold with the hounds; to blow both hot and cold; to say one thing and do another. The allusion is to a cheating game practised at fairs. A belt is folded, and the player is asked to prick it with a skewer, so as to pin it fast to the table; having so done, the adversary takes the two ends, and looses it or draws it away, showing that it has not been pierced at all.