tip (one's) hand
To reveal one's intentions, plans, secrets, or resources. An allusion to letting someone else see the cards one is currently holding (one's "hand"). The foreign leader has definitely tipped his hand when it comes to his country's position in the negotiations. Remember not to tip your hand when you go into the meeting.
tip one's hand
to reveal what one is going to do; to reveal one's secrets. (From card playing.) I didn't tip my hand at all. I left them guessing. They tried to get me to tip my hand.
tip one's hand
Accidentally reveal one's intentions, as in He avoided any comments on birthdays for fear of tipping his hand about the surprise party . This idiom probably alludes to holding one's hand in such a way that others can see the cards one is holding. [Colloquial; early 1900s]
tip your hand (or mitt)
reveal your intentions inadvertently. US informal This expression is the opposite of keep your cards close to your chest (see card).
1966 Martin Woodhouse Tree Frog We couldn't very well oppose it without tipping our hand.
tip (one's) hand
To reveal one's resources or intentions.