The Loch Mess Monster by Helen Lester
Ever since Angus was a wee baby monster living below the surface of Loch Ness, his parents tried to teach him to be a proper monster. But as Angus grows bigger, he gets sloppy. Puggy-nit peanut shells are piling up; his grottie laundry is in a heap; tattie cans litter the floor. It's a mountain of a mess! And as Angus's rubbish heap grows, a surprising Loch Ness sighting of his own awaits on the surface of the lake . . . Children will love the twist at the end of this monstrously funny cautionary tale!