1The nervous twitch in his eye was a dead giveaway that he was lying.
2The politician's lavish spending habits were a clear giveaway of her corrupt intentions.
3Her over-the-top enthusiasm was a giveaway that she was trying to manipulate us into investing.
4The company's sudden interest in environmental issues was seen as a giveaway that they were trying to improve their public image.
5The fact that he always wore a suit to casual social events was a giveaway that he was trying to impress someone.