Calhoun is the current gym and health teacher at P.S. 38. Whenever Coach Calhoun is not teaching, Coach John takes over, much to the kids' dismay. He is commonly called Coach and is a Coach for P.S. 38's basketball and soccer teams. He also is a little league baseball Coach. He is often good with Nate, but has either benched or sent him to detention for various reasons. Coach John may be his friend, but they have differences and Coach Calhoun usually gives kids a chance.
Calhoun coaches the P.S 38 sports teams, which usually lose, but normally it is Nate's fault, as he cannot concentrate well in games.
He also teaches health, and his lecture on puberty was called "Puberty: The Magical Mystical Tour"
Regarding Jefferson, he says that they are all winners, and he appears in a comic saying it is "okay for them to lose".
Calhoun reminds Nate and Artur Pashkov about Field Day. During the event, he made Gina the captain, and he also reprimanded Nate for insulting her. However, before that, Nate was the captain of his fleeceball team in which Gina was in. And Calhoun kept telling Nate to respect Gina though the roles are switched.
- He is rated as 'mad monthly' in Nate's 'P.S. 38 ANGERGRAPH!'
- He is enemies with the Jefferson soccer coach.
- He is a Detroit Tigers fan