a very poor lie which reveals the truth 此地无银三百两

“此地无银三百两”，字面意思是“No 300 taels of silver buried here”，比喻一个人想要把事情隐瞒掩饰，结果反而暴露（A guilty person gives himself away by conspicuously protesting his innocence），可以翻译为“a very poor lie which reveals the truth”。

例句：

你说这话不是此地无银三百两吗！

What you said only gave yourself away.

你这是此地无银三百两，人们很快就会知道是你犯了错。

You gave yourself away by concealing the truth; people will soon find out what mistake you have made.