Frankie is the daughter of Kim, a tow-truck driver who helps Castiel.
Frankie is watching cartoons next to Castiel when he wakes up, having fallen asleep on the couch. She asks if he had a good dream, and Castiel informs her solemnly that he doesn't dream. Frankie then goes on to explain a dream she had about her snot being able to shoot down stars.
Castiel remarks that it must have been a very special snot, much to the girl's delight.