"give oneself away" 是一个反身动词短语，表示（无意中）暴露自己的真实身份、秘密、隐藏的情绪或意图，即“露馅”“穿帮”“泄露底细”。
强调“原本想隐藏的信息因疏忽或细节被他人察觉”，相当于“reveal one's true self/secret unintentionally”。
该短语的核心是反身代词 oneself 需与主语一致（如 he → himself，she → herself，you → yourself 等），常见搭配和语境如下：
主语直接发出“暴露自己”的动作，无需额外修饰，突出“穿帮”的事实。
He tried to act like a local, but his accent gave him away.（他试图装成本地人，但口音暴露了他。）
Don’t smile—you’ll give yourself away!（别笑——你会露馅的！）
通过具体行为或细节解释“如何暴露自己”，最常见的搭配。
The spy gave himself away by checking his watch too often.（间谍因频繁看手表而暴露了身份。）
She gave herself away by blushing when he mentioned the gift.（当他提到礼物时，她脸红了，露了馅。）
说明“被发现的真实身份或状态”，常接名词或形容词。
Her nervous laughter gave her away as a liar.（她紧张的笑声暴露了她在说谎。）
His lack of knowledge gave him away to be a fraud.（他知识匮乏，暴露了自己是个骗子。）
通常不用被动，因为“暴露自己”是主动的（即使是无意中）。若需强调“被他人察觉”，可转换为“sth. gives sb. away”（某物暴露了某人），如：
The way he walked gave him away.（他走路的方式暴露了他。）
日常对话：掩饰情绪或谎言时露馅
I said I hadn’t eaten the cake, but my chocolate-stained fingers gave me away.（我说没吃蛋糕，但沾着巧克力的手指出卖了我。）
侦探/悬疑场景：罪犯或间谍暴露身份
The suspect gave himself away when he couldn’t remember where he was on the night of the crime.（嫌疑人因记不清案发当晚的行踪而露馅。）
社交场合：假装某种身份时穿帮
She tried to pass as a celebrity, but her lack of knowledge about the industry gave her away.（她试图冒充名人，但对行业的无知暴露了她。）
give away：单独使用时可表示“赠送；泄露（秘密）”，但不强调“暴露自己”（如 He gave away the secret. 他泄露了秘密）；而 "give oneself away" 聚焦“泄露自己的信息”。
blow one’s cover：更正式，特指“间谍、卧底暴露身份”（如 The agent blew his cover when he used his real name. 特工因用真名暴露了身份），而 "give oneself away" 更通用。
总结："give oneself away" 是描述“无意中暴露自身秘密或身份”的常用短语，口语和书面语都适用，关键是通过细节或行为“露馅”。