noun. The study of deep, penetrating issues pertaining to the corpus callosum of your tush.
Real citation: “When it comes to sexual taboos however, it becomes a test of tolerance. ‘I don't like seeing a woman's butt crack’ begats ‘Eeeegads! In certain cultures the butt-crack is a symbol of unity and peace! I'm perfectly happy with ass crack!’ which inspires ‘Jesus made you hate buttcracks! Go back to your monastery! I lovez me some buttcracks and have a Phd..in buttcrackology!’ which invites ‘Buttcracks have a right to be seen. Don't like it? Go to another country!’”
(Spackling Compound, Aug. 22, 2005, http://forums.comicbookresources.com/showthread.php?t=75365&page=22)
Made-up citation: "If someone is smart enough to go to medical school and become a proctologist, shouldn't they be smart enough to go to medical school and not become a proctologist? Or was the siren song of buttcrackology just too compelling?"