LORELAI: Think fast [throws them a tee-shirt each]. Tee-shirts for all the girls because I’m the Good Witch of the – hey, aren’t you missing a couple of kids?
Another reference to The Wizard of Oz, earlier discussed. In the film, Glinda the Good Witch of the North (Billie Burke) welcomes Dorothy to Oz, gives her the ruby slippers, and sends her to the Emerald City to find the Wizard of Oz. It is also Glinda who helps Dorothy get home to Kansas. She is a rather glamorous and bountiful mother figure, which seems to be how Lorelai sees herself (and she does help/force Madeline and Louise to get home safely).
The Annotated Gilmore Girls 