Hilda and Zelda prod Sabrina into inviting Jenny over to the spend the night at the Spellman house, ensuring her that they can be "normal."
But things quickly take a magical turn when the Spellman's dryer goes on the fritz and a lint man escapes.
While Sabrina runs to her aunts to check on the lint exterminator, she leaves Jenny alone. Jenny, with her strong belief in other realms (ever since reading The Chronicles of Narnia), opens the Spellman linen closet and is indeed sucked into the Other Realm.
While there, Drell cites the rule against mortals entering his world and turns her into a grasshopper, so Sabrina and her aunts find a way to convince her that the whole experience was just a dream; which is found as one of the official rules "Every rule must have a loophole."
Finally, Jenny believes that she is dreaming and is allowed to leave (in human form).