Slate's Explainer addresses the logistics of how to make a skull bong. Made of a real skull that three teenagers in Houston decided would be a good idea to extract.
"If the skull were too brittle to be easily drilled, the teenagers might have flipped it upside down. Then they could put the slide through the nose as before but use the large hole at the base of the skull—the foramen magnum—as the mouthpiece. The disadvantage of this method would be the tendency for the skull bong to roll over when set down."
I love the seriousness of this article. Very The Onion.