Fake fake blood
We didn't have any real fake blood on the Bad News shoot, so I had to concoct some fake fake blood instead. I used cochineal, glycerine and flour but that stains the skin (you can see the first test's stain on my knuckles). Smearing a thin layer of vaseline on first works nicely to stop the cochineal making contact with the skin, so no stain! After letting the fake blood sit for an hour or so, it thickened and darkened a bit, and ended up looking very realistic.