Rectuma (2003)

Waldo Williams returns from his Tijuana vacation to find out that he had become infected by the Notorious Mexican Butt Humping Bullfrog. After being diagnosed by his proctologist with just days to live, Waldo seeks the help of the mysterious Japanese specialist, Dr. Wansamsaki, who treats Waldo with his unorthodox methods, which involve a long nuclear rod. The next day, Waldo’s rear end starts glowing a bright green – and that’s only the beginning. Within days, Waldo’s rear end develops a mind of its own, becoming capable of breaking away in the middle of the night, committing a mur­der or two and then returning before morning, leaving a fecal trail that leads right to Waldo’s bedroom.