A "sushi" pizza might have worked for me if the crust were perhaps a giant corn tortilla that had been fried, and maybe the sushi rolls were sliced thinner. But honestly the end result would be more like eating some fresh ceviche with nacho chips (which is wonderful!) rather than something I would label a "pizza". The closest thing qualifying it as a pizza would merely be its shape.
The worst pizza's I've had would have to be those super cheap, cardboard like pizzas, with barely any sauce or toppings on them that you can get at your grocery store for like less than a $1, or shrink wrapped in a 3-pack for like $2.50. The cardboard they come packaged on is actually thicker (and perhaps more tasty) than the crust itself. The sauce tastes like watered down tomato soup, and the "cheese" if it's even real, strangely has no flavor at all.
A runner up would be this weird taco pizza that one of our local Pizza Hut's was selling back in the early 90's. It was dough, with refried beans spread on it, then it was topped with cheese and some veggies (like olives and onions). It was a total starch/carb bomb. The refried beans got so dry during the baking process that you would need a whole bottle of pop just to wash down one slice, otherwise you would choke on it. The pizza was even worse as a leftover.
Haha.
