I clung white-knuckled to the back of my friend's motorbike as the two of us zipped around the streets of Hanoi.We buzzed past a man sitting in a barber's chair on the sidewalk of a main road. The man was peering into an oval mirror tacked to a tree as the barber clipped away."See! O.I.V!" my friend said."What?" I asked, trying to figure out what I had seen as much as what he just said."O.I.V.," he repeated. "Only in Vietnam."It was the first day of my 11-day tour through northern and central Vietnam, and the adventure had just begun.Vietnam was never at the top of my list of places to visit -- that is until my old roommate from Atlanta took a job in Hanoi.When my rock-climbing partner, with a level of sanity as questionable as my own,...