Why are you so frightened? Are you afraid of being found out?
Examples (Wiktionary)
Mandarin
但是他们做贼心虚,怕共产党阻挡他们的去路,更怕老百姓骂汉奸。
但是他們做賊心虛,怕共產黨阻擋他們的去路,更怕老百姓罵漢奸。
dàn shì tā men zuò zéi xīn xū , pà gòng chǎn dǎng zǔ dǎng tā men de qù lù , gèng pà lǎo bǎi xìng mà hàn jiān .
But, with the cowardice of thieves, they fear that the Communists will block their exit and, what is more, that the common people will brand them as traitors.