I can't think of the one I use offhand but try searching it on Google or any other search engine. Just type in 'Fake Blood Recipes' and you're bound to get hits.

Just remember, when using Karo syrup wear an undershirt!!!! I found this out the hard way.:( The food coloring turned my skin pink and the syrup ripped hairs off my body. It hurt a lot... but I won first place for scariest costume.:D I did it all myself too! Zombies rock!!!!