It seems like the more I try to remember it, the more I think I can place it, but it's just not coming to me... I just remember the gang was looking for something important, and begged Mr. Haney to let them into the school so they can look (while he thinks they just simply want to go to school on a Saturday), and search all over the classroom, but can't find it.
Again, it's like it's on the back of my mind, but I just can't place it... same deal with the episode itself, it's in the back of my mind, but I just can't place it. It seems like it's something one of the girls lost, either Francine or Muffy... it wouldn't be "Sue Ellen's Lost Diary", I remember that one.