In S1E13, Lorelai tells Rory that she thinks Rory is making friends with Paris, Madeline, and Louise. Rory responds, “Let’s not get ahead of ourselves. They basically just moved of the plan to dump the pig’s blood on me at prom, that’s all.”
“Carrie” is a novel by Stephen King (and a 1976 film adaptation) about an unpopular girl who is the subject of ridicule at her school. She attends the prom, and some students rig the prom queen election so Carrie will win. Then, when she’s on the stage, they dump buckets of pig’s blood on her. Carrie gets revenge through her newly discovered telekinetic powers.