give the game away

US /ɡɪv ðə ɡeɪm əˈweɪ/
UK /ɡɪv ðə ɡeɪm əˈweɪ/
"give the game away" picture
1.

выдать секрет, раскрыть карты

to reveal a secret or surprise, often unintentionally

:
Don't give the game away by telling her about the surprise party.
Не выдавай секрета, рассказывая ей о вечеринке-сюрпризе.
His nervous laughter almost gave the game away.
Его нервный смех чуть не выдал секрета.