[They stop to look at Stars Hollow High, which has been toilet papered by a rival school]
LORELAI: You know, I almost like it better like this.
RORY: It is more festive.
Toilet papering is a common practical joke, prank or act of revenge in the US, where a tree, house, or other building is completely covered in toilet paper. Common events that might attract toilet papering include Halloween, April Fool’s Day, high school graduation, or an important sports match (such as in this episode).
The Annotated Gilmore Girls 