WRAL explains:

To symbolize Duke’s commitment to sustainable environmental practices, recycling and water conservation, the Cameron Crazies – Duke’s enthusiastic student fans – will wear green shirts emblazoned with the slogan, “BLEED BLUE, LIVE GREEN,” the university announced. Duke will purchase carbon offsets equivalent to the electricity, steam and transportation consumed by the game, working in partnership with the renewable-energy company NativeEnergy. The Blue Devil mascot also will have a slight costume change during the game, and half-time entertainment will include a green theme.

Reportedly, Coach K will also mark the occasion by cursing a green streak, working the officials till he’s green in the face, and yelling at them every time they green a call.