It is used for massive mess ups and super fucked up situations, also could be used in epic fails...
"That movie was a total SHITASTROPHY, i slept through the whole fuckin episode"
by Nero Vendetta November 10, 2011
An explosive bowel movement, usually involving an infant or toddler wearing a diaper which was either put on incorrectly or simply could not contain the explosive force of the movement.
My family and I were traveling over the summer and the smell of the car soured quickly. After we stopped and viewed the damage - shitastrophy was the first thing that came to my mind.
by MT - Go Noles October 24, 2008