You will need:
1 Cup of corn syrup
One teaspoon of red food coloring
2 drops of blue food coloring
A teaspoon or so of cocoa powder
Flour and water

Step 1: Mixing

Pour the corn syrup into the bowl add the food coloring (All of it) and mix.

Step 2: Cocoa Powder

Slowly add cocoa powder and continue stirring the mixture.

Step 3: Done

let it sit for ten Minutes at room temperature the stir some more. If its to thin add flour if its to thick add water.
WARNING: This recipe makes a lot of fake blood. These pictures are not mine they are pictures of my computer screen, I did make this recipe yesterday though.