2) cut a hole on each side of the t shirt ( or just one hole in the front if you only have 1 ipad)
3) decorate the hole with red paint to simulate real blood
4) cover the holes from the inside with the ipads
5) get dressed with your new costume
6) ask the party's host if there is a wifi network
7) connecnt both ipads to the network and start a video chat between em with the front facing camera. ( a wireless wifi box will do as well)
if you have an ipad first gen or another tablet with no camera, simply play a video that looks convincing on the device.