The correct response to, "I've got nothing to hide," is a smug, "You definitely have something to hide." Then the person responds, "What are you talking about?

The correct response to, "I've got nothing to hide," is a smug, "You definitely have something to hide." Then the person responds, "What are you talking about?" you say: "I can post it on Reddit tomorrow if you're serious about this." Wait a few seconds, then change the subject.