Braincrusha
Braincrushas are a type of Ork heavy tank. Mounting a massive cannon, the Braincrusha fires gigantic shells at high angles which can decimate enemy tanks.
The Braincrusha cannon fills almost the entire body of the tank so the crew have to squash together in a small tower over the gun's breech, which vibrates with the concussion of the cannon's recoil. The noise and vibrations Ork crew experience while piloting this tank is likely the reason it is called the Braincrusha.
It also has the dubious honor of being literally a moving house with guns with a complementary watch tower on top. Due to the scarcity of images of the Braincrusha let alone models of it due to coming from the old days of yore. The Braincrusha might be the most illusive Ork vehicle to date.