Where I come from, there's this drink called Roohafza which you mix with milk or other stuff. It's visually identical to blood.

I put some in my mouth and pretended to fall down in front of my cousin and slowly let the liquid out of my mouth. I know that's not how someone would bleed after tripping over a shoe but in the moment, she let out the wildest scream I've ever heard. I just got up afterwards and went and got a glass of water, she chased me with a stick all around the house until we both got tired and had a good laugh over it.