AustLit

'A boy is given underpants that, despite their look that would cause him to be teased by the school bully, give him superhuman strength. But when he takes a break during a cross-country race (he is first by a wide margin), those underpants start to shrink, and the bully eventually comes to steal the rest of his clothes. He ends up going home in the nude, causing him to be grounded, but he eventually enters a mouse race in which the winner gets 50 dollars. The boy wins the mouse race by giving the mouse the pants. Was later adapted as an episode of Round The Twist.' (https://en.wikipedia.org/wiki/Unreal_(short_story_collection)

'A boy reports seeing a flying dog, but his family does not believe him. He is bet a thousand dollars if he can prove he saw one, or three years of washing if he can't.'  

(https://en.wikipedia.org/wiki/Uncanny_(short_story_collection))

'A boy is at risk of getting kicked out of his flat, because he has a dog that flatulates because it can't bark.' (https://en.wikipedia.org/wiki/Tongue-Tied_(short_story_collection))

'A boy gains the ability to hypnotise chickens. He later tries it on his best friend, then takes it to the next level by making his best friend remember his past life, but with disastrous consequences. Was later adapted as an episode of Round The Twist.'  (https://en.wikipedia.org/wiki/Unbearable_(short_story_collection))