Human-sized again

Cassie looked around, and spotted a banner hanging between two buildings just above street level, advertising an upcoming event. She bent over to retrieve it, although as she did she heard whooping and cheering behind her, as well as several car horns, as she bent with her giant-size posterior directly towards the crowd. Blushing even more, she spread one hand over the expanse of her behind and crouched instead, to the audible disappointment of her admirers. She snatched up the banner, easily pulling it away from its fastenings, then stood back up to her eighty-foot height. If she were her regular size the banner would easily cover her, and if she had shrunk to her ant-size it would swamp her, but as a giant girl it was barely going to cover any part of her modesty. Still, she wrapped it around the parts of her that she deemed the most urgent, covering her privates and a strip across her rear. With the banner in place she tried to tie it at her side, but found it would not quite reach.

"Come on..." she grunted, pulling the ends to make them reach enough to knot. With one last tug, the banner tore in half, and she was completely nude again, holding the two halves, neither of which were long enough to do anything practical with. "Of course, why would things start going right?" Cassie sighed as she resorted to covering herself with her hands again.

"Cassie!" Hope flew up in front of Cassie's face again, the girl had to squint to see her, going slightly cross-eyed to focus on the tiny form. "I've got the answer!" Hope held an object too small for Cassie to see, but she could make out a tiny red glow from it, which she hoped meant Pam particles, which could shrink her down.

"Come on, then, before someone calls out the army on me!" Cassie said. Hope made a throwing motion with her arm and something resembling red glitter flickered in Cassie's direction.

For a few seconds nothing happened, and Cassie began to wonder if Hope had developed a sense of humour and had faked having something to help her. Then she suddenly felt herself becoming lightheaded, and the buildings around her seemed to blur and sway, before either they shot upwards or she shot downwards, she wasn't sure. The ground raced up to meet her, and Cassie fell forwards, tumbling into a pile of cardboard stacked in an alley.

"It worked." Cassie sighed as she got to her feet again, once again the size of a teenage girl, "It worked!" she pumped a fist in the air, then wrapped her arms back around herself as she realised she was normal-sized, but still completely naked. She realised something else as she looked around, "Wait, where the heck am I? And how do I get home like this?! ...Hope...?"