Caillou Meets Robbie is an episode in season 1.
Caillou is at the park. He is on the swings and sees a boy about his age. His mommy says he can play with him so he walks up to Robbie and taps his shoulder. Robbie is scared so he runs to his mom crying. Caillou is sad so he askes Robbie's mom why he didn't like him. She said Robbie is deaf. Caillou askes "What does that mean?". Robbie's mother says it means he cannot hear. Robbie gives Caillou another chance and they go to Caillou's house. Robbie and Caillou color and Robbie breaks Caillou's crayon. Caillou is used to that with Rosie and says it's OK. When he leaves, Caillou is very sad and wants to play with him again.
Robbie cameos in more episodes as a townie of the neighborhood.