Rob Lloyd Jones 
Me, My Brother and the Monster Meltdown [PDF ebook] 

Comedy chaos breaks loose when two brothers’ imaginary monsters come to life — in the supermarket! A laugh-out-loud adventure for fans of Dogman, the Treehouse series and Pamela Butchart books.All the adults are freaking out. Giant monsters are smashing up supermarkets across the country. The army can’t stop them and the prime minister is hiding in panic. A colossal six-headed gingerbread man, a massive emoji poo, a gigantic bouncing bum… Top scientists have no idea where they come from — or why they seem to hate supermarkets so much. But nine-year-old Otis has an idea. The creatures are exactly the same as drawings by his five-year-old brother, Jago: what if Jago brought his crazy creations to life with a magic pen? But their parents won’t listen, so it’s up to Otis and his pals to sort this monster mess out!