B&W#028: Gravity Cavity
Newton's law of universal gravitation states that every well-lubed rectum attracts every oversized dildo in the universe with a force that is directly proportional to the product of the ass's mass and inversely proportional to the square of the distance between the dick's silicone core.
...Or something like that, I dropped out of school to study drawing realistic horse penises instead so some elementary stuff like that is beyond me.