look up any word, like sex:
To keep to oneself, to be secretive, to be very cautious in one's dealing with people and giving nothing much or nothing at all away. (As if one were playing cards and not permitting anyone to see any of the cards.)
"He is very cautious. He plays his cards close to his chest."

"You seem to be playing your cards close to your vest."

"Roy likes to play his cards close to his chest"

"To play one's cards close to one's chest is not nice etiquette"
by aussieboy322 June 06, 2009