back when the 6th book came out, someone posted a video of this dude driving around at midnight yelling the ending of the book to all of the people at a Barns and Noble.  The guy was kinda pussy about it, cause he didn't yell loud enough and create a scene but it was still fuuny as hell non the less.
If I would've known the ending and thought of that, i would've got my uncle's fireman's megaphone, and made sure the whole parking lot + everyone in the store could hear.
I like and read the harry potter books, but doing that would be priceless.