Graham Smith

When a man drives by the strip at Lumley Beach in downtown Freetown at night, he'll probably hear a sharp hiss. That's not an unusual sound in Sierra Leone. People hiss instead of whistling — to get your attention, to call for the bill at a restaurant, to buy a bottle of water on the street.

But the hissing along a stretch of beachfront road at Lumley Beach has a different purpose. It's the sound prostitutes make, and they've perfected the hiss. That's why they're called serpents.

When my NPR colleague Tom Bowman and I visited the southern Afghan district of Arghandab in the fall of 2009, we headed out on patrol with the U.S. Stryker battalion. We soon found ourselves in the middle of a firefight. A U.S. vehicle was blown up and two Americans were killed in an attack that was all too common at the time.