In a 2004 study performed in Europe, volunteers at a beach were provided with sunscreen and told they'd be evaluated on how well they used sunscreen. Even though volunteers had every reason to be diligent about sunscreen application, researchers found that the participants rarely applied the product to the tops of their feet. When asked why, 50 percent of the participants said they didn't want sand to stick to their feet [source: Lademann et al]. While the sensation may be unpleasant, our feet are just as at risk for skin cancer as the rest of our body. According to the American College of Foot and Ankle Surgeons, skin cancer on the foot often goes unnoticed because people don't check their feet as diligently as they check other body parts [source: Medical News Today]. Lessen your risk for skin cancer and flip-flop tans: apply sunscreen to your feet.