informal something that tells or shows something secret, often without intending to顯露(某人)的感情;暴露(某人)的内心世界
He said he'd given up smoking, but the empty packs in the bin were a dead giveaway (= clearly showed the secret truth).他說他已經戒煙了,但是垃圾桶裏的空煙盒讓他徹底露了馬腳。