Weirdo Halloween (Goosebumps Horrorland) by R,L Stine
Chris and his twin, Meg, have a problem. It started the night before Halloween when the twins found a gang of bullies hassling someone in costume. The twins rescued the kid - only to find that it was a bald, pink alien who promptly swore allegiance to them. 'Weirdo' is smelly and gross with a lot of disgusting habits, and the twins can't shake him. Little do they realise that their troubles are only beginning. Weirdo's invited hundreds of aliens to town on the 31st for a full-scale invasion - and to come live in the twins' house! Will the HorrorLand souvenir save them - or harm them?!