Aw. That's no good. D8
Well, I've got plenty of prank ideas to share. A pretty good one that didn't happen this year (everyone at my house expected it - which is probably why it didn't happen) is bubble wrap under the doormats. I mean BIG bubble wrap, the kind that makes a really good noise when you step on it. Scares the hell out of everyone.
My brother and I also scared somebody pretty well one year by strategically taping Wolfpack poppers, those little firework things that make a loud SNAP sound, to the underside of the knocker on our front door. We couldn't find any poppers this year, though.