Sports Illustrated pulled out all the stops for their Summer of Swim series in honor of the Fourth of July. Cover girl Hannah Davis stripped down to her skivvies?if you can even call them that?against an American flag background. The 25-year-old beauty flaunts her killer physique all throughout the patriot-themed spread, and posted a slew of other photos from the Justin Marquis shoot. If anyone knows anything about the model, its that she's totally fine with baring her all for a good cause. After receiving flack over her nearly nude SI cover back in February, Davis stood up for herself and the amount of skin shown on the magazine.