What's a good iOS game for makin' creepy sounds, like for messing with the guys on the job site?

Alright, so I downloaded this Spooky Beats Maker: Horror Mix thing. No BS, it does what it says. You can whip up some seriously messed-up sounds with it – perfect for when Ramirez is usin' the porta-potty. The interface is kinda clunky, like somethin' a teenager threw together, but I figured it out without the tutorial (which is useless, by the way). Battery life seems okay so far, lasted through lunch and a bit of the afternoon. It's not gonna win any awards, but for a free app, it's actually rugged enough for a job site prank. I wouldn't trust it to survive a drop from the scaffolding, but it's survived a few accidental bumps already. Just watch out for the ads, they can be a pain in the rear.