An inordinately large poop, in which the person defecates so hard and for long that he/she has no choice but to declare a "sushdump." It usually involves going to the bathroom for an extended period of time, and leaving a long-lasting stain (offensive to the senses of smell and sight) on the toilet.
Dude, don't go into that bathroom for another four hours. I just took a massive sushdump.
by KidParkinsons April 24, 2008