The answer to this question can be found in the chapter entitled "December," which is when Holling both has his debut performance as Ariel in Shakespeare's The Tempest but also has the chance to meet Micky Mantle, one of his heroes, a famous baseball star. As a result, Holling finds that he rushes out into the streets dressed as Ariel in a rather strange costume to catch a bus to take him to the stadium. Note how Holling describes himself as he waits outside of the theatre hoping for a lift to the stadium:

Standing on the street in front of the Festival Theatre in bright yellow tights and a blue floral cape covering white feathers on his butt--this was not an Ariel in a happy holiday spirit.

We can understand therefore why it is that the bus driver is rather perplexed at what precisely he has picked up, and asks the question you have quoted above. Holling, perhaps grasping around for inspiration, answers him by saying "John Wayne." Even though the bus driver is not convinced, he eventually takes Hollling to the stadium and gives him a baseball for Mantle to sign.