Making and taking a hit chest to chest, instead of skull to skull, is easier to remember if you're not wearing a helmet, say University of New Hampshire Wildcat football players. Jack Rodolico/New Hampshire Public Radio hide caption

itoggle caption Jack Rodolico/New Hampshire Public Radio

Tornadoes killed at least 17 people on Sunday and Monday. But some managed to stay safe in underground shelters like the one at right in Vilonia, Ark. Karen E. Segrave/AP hide caption

itoggle caption Karen E. Segrave/AP

Bartender Matt Carucci says he rarely feels safe biking in the city but often rides without a helmet anyway. "There are a lot of other ways to hurt yourself," he says. John Rose/NPR hide caption

itoggle caption John Rose/NPR