Make a Marshmallow Blow Gun out of PVC Pipe. To shoot, simply stick a mini marshmallow in the end of the gun and blow. The amount of air power is important. This would definitely make a great project (Bottle Rocket Pvc Pipes)
Another pinner said: "This isn't MY door, but I did this too. Unfortunately, I didn't get a picture of it though. I used an inexpensive, green, plastic table cloth and a Sharpie to make a giant Creeper face.