Ahh, the joys of a black cake.
Here are Laura & Elizabeth (film) & Katy (photo) partaking of Katy's 14th Birthday cake, which was black with red-rimmed eyes and a blood spatter, My Chemical Romance stylee.
I recommend to all parents of sneaky children icing cakes in black. Not only is it enormously satisfying to mix (mmm, sugary tar), you know straight away if they've been eating it by the goth-lipstick the black icing gives them. Result!