When Princess Peach is snoozing safely in her castle and all is well in Mushroom Kingdom, how do you think Mario spends his free time? Lifting weights? Scarfing down pizza? Heck no! He attends medical school! Mario earned the title "Dr." in 1990, and immediately began battling flu bugs and squashing germs on the original NES. Since then, he's fought disease on Game Boy and the Super NES, and now he's moved on to deliver vaccinations and vanquish viruses on Nintendo 64.