If those zombie mouth cupcakes weren't enough for you, here's a recipe from How To Cake It developed to help bakers make their own realistic brain cakes. It basically involves making a mound-shaped cake (in this case red velvet), then covering the exterior with ropes of fondant and raspberry jam. That...is pretty realistic looking. I have never seen a brain in real life but I imagine that is what it would look like. Did I almost puke just looking at it? Yes. "Pretty sure that was a fart." IT WAS A DRY HEAVE.
Keep going for a video tutorial, text recipe with pictures available HERE.
Thanks to McCray, who just wants a cake that looks like a cake, but then on the inside looks like blood and guts and pieces of bone.