okay so basically, take a tank. but the tank it two-stories tall and 75 meters across.
mounted on top is a giant fighter jet that acts as the cabin to the whole monstrosity.
It has two cannons that fire rocket propelled robot sharks with chainsaw teeth. then there are anti air guns mounted on the back that fire nukes at enemy planes cause... well, fuck em.
also there are 50 cal. machine guns mounted under the tank aimed specifically so they target the crotches of anyone standing ahead of it. Oh and the outside has giant surround-sound speakers that blast dubstep.
24/7.