I [Jesus] am he which searcheth the reins [kidneys] and hearts. Revelation 2:23
Yes, it's true. Jesus is going to search through your kidneys. And if he doesn't like what he finds there, he's going to send you to hell.
You see, according to the Bible, your conscience is in your kidneys (called "reins" in the King James Version). So by inspecting them, Jesus can tell if you've been naughty or nice.
Here are some other verses that give a God's eye view of kidneys.
Oh let the wickedness of the wicked come to an end; but establish the just: for the righteous God trieth the hearts and reins. Psalm 7:9
I will bless the LORD, who hath given me counsel: my reins also instruct me in the night seasons. Pslam 16:7
Examine me, O LORD, and prove me; try my reins and my heart. Psalm 26:2
Thus my heart was grieved, and I was pricked in my reins. Psalm 73:21
Yea, my reins shall rejoice, when thy lips speak right things. Proverbs 23:16
But, O LORD of hosts, that judgest righteously, that triest the reins and the heart. Jeremiah 11:20
I the LORD search the heart, I try the reins, even to give every man according to his ways, and according to the fruit of his doings. Jeremiah 17:10
But, O LORD of hosts, that triest the righteous, and seest the reins and the heart. Jeremiah 20:12