Greg James joins a star-studded crew including Dara O'Briain, Chelsee Healey, Mel C, Jack Dee and Phillips Idowu for a gruelling five-day, 110km whitewater canoe expedition down the Zambezi River in Zambia for Comic Relief. The challenge raises over £1.1 million, and Greg famously strips naked to jump in the river after listeners donate an extra £50,000.