Zombie walk, need to make fake blood I can wash out. How do I do it?

I have an event called the Zombie walk coming up in my town and I need to dress up as a zombie. The thing is, my outfit, I wanted to wear a lolita WHITE dress, but to add a zombie effect, I want to splash blood on it. Does anyone have a recipe that they know will wash out of white clothing/not stain? Thanks.