Andy and Terry's amazing treehouse now has 13 new storeys, including a tiny-horse level, a pyjama-party room, an Underpants Museum, a photo-bombing booth, a waiting room, a Door of Doom, a circus, a giant-fighting-robot arena, a traffic school, a water-ski park filled with flesh-eating piranhas and a treehouse visitor centre with a 24-hour information desk, a penguin-powered flying treehouse tour bus and a gift shop.