WARNING: This post contains vague film history and trivia.
Alfred Hitchcock, the Master of Suspense, may also be the grandfather of kitchen condiment special effects. Not worried about matching realistic colors on black and white film, he used chocolate syrup to create the bloody shower scene in Psycho (1960).
Thus began the popularity of using household pantry supplies to create horror movie effects.
With the growing use of color film, directors experimented with ketchup, jellies, food coloring, and even animal innards. George Romero and Tom Savini were one pair whose efforts brought us closer to the true color and texture of blood splatter and spilled guts.
Even Robert Rodriguez, director of such horror greats as From Dusk Til Dawn and the Spy Kids trilogy, has used this method. In one scene of Once Upon a Time in Mexico, Rodriguez used raw chicken skin to simulate wounds on a victim of an interrupted facial surgery.
All this extra food product – ketchup, pig intestines, chocolate syrup, etc. etc. – adds up to one very important thing for monsters: taste. Monsters know that when they hang out behind the set they can skip the sandwich trays and sushi rolls. There are fresh victims baking under the bright set lights, waiting for a smoke break, with no fear of attack when the cameras aren’t rolling. And they’re already covered with our favorite toppings!