wear one's heart on one's sleeve（把情感表露出來）

意思是"to make one's intimate feelings or personal affairs known to all（張揚，外露，坦率）"，尤指感情上的外露；其實也就是"expressing your emotions freely and openly ...（大膽的說出你的真實感受）"。

請看例句：

She's a shy person. She's never been one to wear her heart on her sleeve.

她是個害羞的人，從來不敢把心里的真實想法表達出來。

Alan: This is life and death. Your wife is lying in a coma. You, you don't even make a pretense of caring, do you?
Alan：這是生死大事，你的妻子正處于生死狀態，你連假裝關心下都不行嗎？
Claus: Of course I care, Alan. It's just, I don't wear my heart on my sleeve.
Claus：當然，我當然關心啦，只是我不擅于言表而已！

BTW: 這段對話是出自《Reversal of Fortune（命運的逆轉）》