Meeting with guy I met online-how do I explain to my parents?

Okay, I’ll start with the basics: I’m seventeen, and a few months back I began talking to a guy I met on a social site who is the same age. After talking to him for awhile, I realized we have quiet a bit in common in interests and ideas. I’ve seen several pictures of him with look fairly authentic, including a few with his sister, who he also has as a friend on a social site (and I’m doubting a fake would go to all that trouble). He also lives in the same city.

Now recently, the both of us have decided we would like to meet up sometime. Now, before all of you start freaking out at me, telling me he’s some digusting perv and I’m going to get raped and all that, let me explain a few things:

1. We’d be meeting in a crowded area, probably a mall
2. I’d be bringing my friend and her boyfriend along, partly to make it a double date, but mostly just in case there is a small chance this guy is a fake/creep

Now, this sounds all good and thought out, but there’s a problem: My parents. I have no idea how to explain this to my parents. I know they wouldn’t approve of someone my age meeting up with someone I met online. I considered lying about how I met him at first, but then decided not to as I would end up feeling terrible about it and the truth would probably end up slipping out later.

Has anyone here ever been in this situation? Even if you haven’t, could you possibly give me a little advice on how to explain this to them? Please help, I’ve never had any luck with relationships and I would like to see how this turns out.