The nothing to hide argument is quite popular and maybe even you have used it before. However, it’s quite a weak argument, so here are some quotes to help you fight it.
Arguing that you don’t care about the right to privacy because you have nothing to hide is no different than saying you don’t care about free speech because you have nothing to say.
Here’s my email address. What I want you to do when you get home is email me the passwords to all of your email accounts, not just the nice, respectable work one in your name, but all of them, because I want to be able to just troll through what it is you’re doing online, read what I want to read and publish whatever I find interesting. After all, if you’re not a bad person, if you’re doing nothing wrong, you should have nothing to hide.
Glenn Greenwald in Why Privacy Matters