NASA engineer Mark Rober used some red sauce and two iPad 2s in order to pretend, at whatever Halloween convention he might be attending, that he has a vast, open, and bloody wound through the core of his torso.
Relatively simple Halloween costume using 2 iPad 2s to make it look like you have a huge hole in your torso. You'll also need a MiFi hotspot (if you don't have a WiFi network available where you want to use the costume). Basically you start a FaceTime chat between the iPads and then tape one to your front and one to your back. Add a little red paint and you're good to go. It's supposed to look like you have a gaping hole in your torso. If you spend more time than I did on the blood and the flesh part and lining up the iPads it could look pretty cool.