Noun; An anal orgasm occurs when you hold in a monster shit for too long and finally let loose. After enough time passes, the levvy will break on brown river, and the feces flood will pour out. The quality of an anal orgasm (or simply "AO!") is dependent upon the girth of the ass tremors which create this unnatural disaster. When the eruption occurs, it will feel plain magical, but be forewarned; it is best to be in the vacinity of a T-bowl or else you're going to have a grizzly poo-lava mess on your hands.
"Holy Cow, Brandis just had an anal orgasm in the bathroom that registered a fuckin' 12 on the Richter Scale! Not only am I still shaking from her not-so-humble rumble, but the smell is just plain fuckin' killing me."