Both the small girls started to make out with other right infront of Timmy ignoring the fact that they were still shrinking.
As Timmy watched he noticed that the sexual arousal only seemed to prolong the shrinking process; making the two girls shrink and shrink till their height could no longer be measured in meters but in centimeters!
Timmy wasn't quite sure what he was feeling while watching the two girls shrink; arousal, fear they'd shrink too small or the fact that they were too small now to use the ray gun they had grabbed from him earlier.
The girls stopped kissing and fondling each other and finally noticed reality around them. Timmy was holding the ray gun in one hand and in the other he had opened his bag to scoop the two naked girls into.
A few squeaks later from the girls; Timmy closed his bag with the girls and their clothes inside and then ignored their friends who walked past him searching for the two girls.
As far as reality was concerned the two girls had always been that small except for Timmy and the two shrunken girls who knew better.