"Oh no, I'm getting smaller!"
Archie was now much less than half his proper height, less than a quarter even. He managed to craw out of his clothes before reaching up helplessly toward the garden furniture he'd been sitting in, which now towered above him. He hoped he wasn't about to simply shrink away to nothing.
It was when he was naked when he noticed bumps on his sides that he could wiggle back and forth. They seemed to be getting longer as he watched.
Soon Archie's whole body started to lengthen and thin out. His eyesight got pixelated as his eyes split up into compound lenses. He twitched his six limbs with some urgency as he also felt his mouth changing. It turned into a pair of insectoid mandibles sticking out in front of him. It felt like he was opening his mouth sideways, and as he looked around he could tell he was still getting smaller.
"Am I turning into a bug?" he wondered. His nose closed up, and air stopped flowing through his mouth and started flowing in through his chest, or rather his thorax. As if to answer his question, a pair of thin protrusions pressed out between his eyes near where his nose had been. They stretched longer and longer and started twitching to sample different positions in the air. He could smell the grass and dirt and what he would soon discover to be pheromones from the other insects around him. Soon they were so long he would have thought they were huge, but the were only long in proportion to his shrinking body.
He couldn't help but wonder what was happening to all of his body mass as he noticed that even his shoes were now larger than him. His arms and legs had stretched and thinned and no looked almost identical to the appendages that had grown out of his middle. He was resting on all six of them, and they all had a surprisingly good grip on the ground beneath him from what he could tell. At last he was a three-inch long insect with a thin body and relatively long legs. He instinctively froze up and stood still before getting an urge to jerk his stick-like body back and forth. He was able to start walking on his sex legs over toward the nearby tree, and he knew it looked way more awkward than it felt. He wondered what he had become and why.
In fact, he had become a rather common but inconspicuous species of stick bug.