Dip the paint brush in the red paint and flick red paint onto the hung tarp, creating a blood splatter effect. Start in the middle of the tarp. (If you get too close to the edge, the paint might spatter off the sides, getting your yard or garage paint-splattered.) Randomly spatter paint and brush paint in a slashing motion all over the tarp. You can also write “Help” or “Beware” or “Die” in messy brushstrokes.
When it looks sufficiently bloodied, put on the rubber glove and dip your hand into the paint. Make a few bloody handprints. I liked the effect of dragging my hand across the tarp. Like the victim was trying to escape or something. (I like to think I am theatrical and not a sick, sick person.)
After the paint drips down the tarp to your liking, lay it flat to dry. Takes a few hours to dry.
Repeat the process for the other two tarps. (One tarp could be enough, depending on your party needs, but a quart is enough paint to do three tarps, and since the tarps cost about $0.79 apiece, why not do more? Go big or go home.)
Now it’s time to decorate your party space! The plastic tarps I used were so light that I could hang them by duct tape, or in places, by tucking the tarp under something heavy on a high shelf, or by poking a preexisting nail through the plastic.
When the party is over, fold the tarp gently, paint-side-in. Note that a bit of the paint may chip off in places, so when you open it next year, maybe open it outside first so you don’t get red paint chips in the house.
Caution - bloody tarps may cause guests to pretend to stab each other.