D.B. Cooper was the name that reporters gave to a man who, in 1971, hijacked an airliner, extorted $200,000 from its owner (Northwest Orient), and parachuted off the airborne plane with 21 pounds of $20 bills strapped to his body. He was never caught, and it is generally assumed that he did not survive his parachute landing.
After the boys ride their canoe over the waterfall, Jerry and Dan ask Tom where he was a river guide. After he tells them where, he also says he was Employee of the Month. Which was also a lie. Dax Shepard goes on to play Vince, in the film Employee of the Month in 2006.