Stack is the "cause célèbre" of many fascinating anecdotes during the course of his life and running career. He was long a card-carrying, dues paying member of the Communist Party. In 1982 he participated in the Ironman Triathlon in Hawaii, and he holds the event record for most time taken to finish, in dead last place. Surviving the ocean swim rather effortlessly, Stack commenced the long bike ride on his single speed granny-basket bike, and finished the marathon run early the next morning, but not before stopping in for a full waffle breakfast prior to finishing. Stack finished in the record-breaking time of just over 26 hours. Officials implemented a cut-off time in subsequent years.