Did Graham Nash Write “Just A Song Before I Go” On a Bet?

Yes he did. Graham was at home in Hawaii, about to go off on tour. The guy who was going to take him to the airport said, 'We've got 15 minutes, I'll bet you can't write a song in that amount of time." Before they got to the airport, the lyrics were completed.
Going to the airport and his travel day ahead was on Nash's mind, so that's what he wrote about: "driving me to the airport and to the friendly skies."  "Just a Song Before I Go" was written for his friend who made him the bet. I wonder what he got for winning?