How often do you chuck your jeans in the laundry? If it's more than once a year, the CEO of Levi's thinks you're doing it wrong. At a green-themed conference sponsored by Fortune, Chip Bergh said he practices what he preaches. "These jeans have yet to see a washing machine," he said of the pair he had on, which he has owned for a year. "I have yet to get a skin disease." (Bergh didn't say how often he wears them.)