A better recipe for fake blood?

We have a school project in media where we have to create a short scary/thriller/horror movie without using special effects (meaning we can't edit the footage except for cutting it) and for just one scene we need some blood. We tried using corn syrup and food coloring, but it looked sort of fake and lolly-like, even when we added coffee powder or hot chocolate mix. We can make it look realistic with lighting, but then that makes the rest of the scene look bad. Does anyone have a better recipe?