After meeting Bodie for the first time Johnny engages in a football game with him. Johnny tackles Bodie in the surf and they get soaked. When they "come out" of the water Johnny's shirt is dry. Watch it when he starts to walk and it is really obvious.
You need to watch the scene again. He's wearing a grey shirt, it is still wet when they come out of the water. Maybee the nightime threw you off, but both of thier shirts are still wet.