The purple light only lasted a few seconds, but when it was gone, something was definitely different, because Dawn was no longer behind the counter. Instead she was sitting at the table across the diner,
"How did I get here?" she asked, but it wasn't her voice. It was a little boys
looking down she was now a little boy, but she couldn't feel a penis, like she expected, She looked down opened her pants and found that she had a vagina, one of a little girl's it seemed but she was a boy... she decided that being that she magically transformed into a little boy, it wasn't much farther to change her/his genitals as well
Dawn looked around the room and saw that everyone was having a similar reaction. Kids were looking around the room, then realized something was wrong... or technically right with their genitals their clothes remained the same, so it looked like they were wearing their parents' clothes. They all must have been around 7 or 8 years old.
Dawn saw where she had been standing earlier, and saw a mirror image of herself as a kid, sitting on the ground wearing an oversized waitress uniform, and she saw her child doppleganger raising a tent in her skirt