"Sonya, be a kangaroo!"
Fur started sprouting all over Sonya's body while a huge tail sprouted from her rear, ripping her knickers. Her legs changed to become more powerful and her feet grew to massive footpaws. She wriggled her toes, and saw that she had gained a pouch.
Above the waist nothing much had changed apart from being covered with fur, gaining a slight bit of girth, having claw-like nails and of course her head, which had changed shape while her ears had grown.
"Wow, this is amazing!" she said as she stood up, looked in the mirror and did a few hops, the floorboards shaking under her huge feet.
"Your pouch looks cosy." said Derek "Shame I'm too big to fit in it - unless..."