- show one's hand
- show one's handFig. to reveal one's intentions to someone. (From card games.) •
I don't know whether Jim is intending to marry Jane or not. He's not one to show his hand.
•If you want to get a raise, don't show the boss your hand too soon.
* * *{v. phr.} To reveal or exhibit one's true and hitherto hidden purpose. * /Only after becoming Chancellor of Germany did Adolf Hitler really show his hand and reveal that he intended to take over other countries./
Dictionary of American idioms. 2013.