play2 if you play with fire you'll get burnt proverbial saying, late 19th century, meaning that if you involve yourself with something potentially dangerous you are likely to be hurt. A similar thought is found the mid 17th century, in Henry Vaughan's Silex Scintillans (1655), ‘I played with fire, did counsel spurn…But never thought that fire could burn.’
play both ends against the middle keep one's options open by supporting or favouring opposing sides.
play it again, Sam popular misquotation of Humphrey Bogart's words ‘If she can stand it, I can. Play it!’ in the film Casablanca (1942), subsequently used as the title of a play (1969) and film (1972) by Woody Allen.
play the — card introduce a specified (advantageous) factor; the term derives from a comment made in 1886 by Lord Randolph Churchill on Gladstone's handling of the Irish Home Rule question, that ‘the Orange card would be the one to play’.
play the game behave in a fair or honourable way; abide by the rules or conventions. Recorded from the late 19th century, the phrase is particularly associated with the appeal to public-school values enshrined in Henry Newbolt's poem ‘Vita Lampada’ (1897).
play to the gallery act in an exaggerated or histrionic manner, especially in order to appeal to popular taste; the gallery here is the highest of the galleries in a theatre, containing the cheapest seats.
those who play at bowls must look out for rubbers proverbial saying, mid 18th century, meaning that one must beware of difficulties associated with a particular activity; a rubber here is an alteration of rub, an obstacle or impediment to the course of a bowl. Shakespeare in Richard II (1595) has, ‘Madam, we'll play at bowls.—'Twill make me think the world is full of rubs.’

See also when the cat's away, the mice will play, play chicken, play ducks and drakes, play second fiddle.