The strength of movie making is often the thrill and delight an audience receives from watching realistic portrayals of situations. Films can properly accomplish this without directly showing actions as they happen, but by instead relying on creative camera angles and effective, suggestive acting, while allowing the viewer to fill in any visual blanks with her own imagination, while viewing the results. This method is especially true when depicting violent or gory situations, such as when one character stabs another.
Mix one tablespoon of water with one cup of clear corn syrup in a bowl. Add drops of red food colouring, and stir the mixture with a whisk.
Stir in a small bit of chocolate syrup, using a whisk, to give this fake blood the desired, realistic consistency. Allow the mixture to sit for about 10 minutes.
Place one video camera in a position to capture one actor's stabbing motion towards the victim.
Position a second video camera on the opposite side of the victim, so that the victim's body blocks the camera from actually seeing the knife "entering" the victim's flesh.
Film the action. One actor stabs towards the victim with a retractable plastic knife, caught by the first camera. With the second camera, capture the victim's facial reaction as he is stabbed, which may include spitting out the edible fake blood.
Smear the fake blood onto the victim's "stab wound." Film the wound and the aftermath of the stabbing.