You're not sure exactly what will happen when you attempt to shrink Kristen while she's holding you in her fist. How smart is this gun? If it shrinks clothes along with people, will it know you're not just an accessory on Kristen's hand? What if you shrink her to an inch tall, but that makes you so small that you still fit into her hand? You'd be just as screwed, and smaller than a speck of dust.
Fortunately, that's not how it goes. The mountain becomes smaller and smaller, and by the time Kristen realizes what's happening, she's no longer powerful enough to crush you like a bug. Soon, you're a few inches taller than her, just as in real life.
Or you would be, if you were normal-sized. The difference between your heights now cannot be measured in inches. No, you take a look around and discover that the two of you are probably now no more than a quarter-inch tall.
You're both a little dazed at all this size-changing, neither paying a ton of attention to the other.