Correct

露马脚

/ lòumǎjiǎo / 
Strokes

Definition

to reveal the cloven foot (idiom); to unmask one's true nature/to give the game away

Example

As a Verb

give the show away; give oneself away; betray oneself; let the cat out of the bag

1
Wǒ
我
yī
一
shuōhuǎng
说谎
jiù
就
lòumǎjiǎo
露马脚
  
。

Whenever I try to tell a lie, I give myself away.