Fake blood is used for pranks, in theater, on film, and during a certain ghoulish holiday at the end of October. The number of recipes for fake blood is as numerous the options for its use. Some recipes rely on a corn-syrup base, while others utilize the same stuff that makes Jell-O so wiggly: gelatin. Alfred Hitchcock is said to have used Bosco chocolate syrup during the memorably bloody shower scene in "Psycho". Kool-Aid powder is another oft-used ingredient due its high amount of red food coloring.
Combine the water and flour in the pot. Stir until thoroughly mixed.
Bring the mixture to a boil. Stir with a small whisk while the mixture boils for three minutes.
Simmer mixture on low for 15 minutes.
Remove the pot from the stove and allow the mixture to cool to five minutes.
Stir in the package of Kool-Aid powder. When the mixture has cooled, it is ready for use.
Add flour to the flour-water mixture if you think it is too thin. Fake blood must be appropriately thick to be believable.
Never apply the mixture to your skin before it has properly cooled. This can cause severe injury.