Lorraine and John first become involved with Mr. Pignati when they are prank calling people. Lorraine is supposed to choose a phone number randomly from the phone book, but she chooses a number based on a neighborhood address. While speaking to Mr. Pignati, she realizes how lonely Mr. Pignati is. Unfortunately, Mr. Pignati is not only lonely but trusting, so he is more than willing to donate to their fraudulent "L & J Fund." Lorraine and John make arrangements to pick up their ten dollar donation the following day.
When John and Lorraine go to his house the next day, Lorraine has second thoughts about pranking Mr. Pignati. She realizes that he lives alone in an untidy home, and she is also fearful about what he could do to them. While visiting him, Mr. Pignati shows them his collection of pig figurines and invites them to go with him to the zoo the following day.
The relationship between Mr. Pignati, John, and Lorraine develops because of their collective loneliness and isolation. By confiding in one another, they develop a support system that all of them lack. Their relationship is ultimately destroyed by John and Lorraine's betrayal of Mr. Pignati's trust because they not only throw a party in his home, but disrespect his private belongings that symbolize his life with his deceased wife.
Lorraine and John get involved with Mr. Pignati (the Pigman) through a random telephone prank. They choose him to follow because they are social outcasts themselves and do not have the best intentions for befriending Mr. Pignati. Basically, they want to take advantage of him by chronicling their interactions. They feel this gives them an advantage. The story was written in 1968, so it is a version of cyber-bullying.
Going beyond the surface, the two become involved with him for several reasons. It allows John and Lorraine to form a bond through a shared secret oath. This gives them sense of belonging and fills, in part, the loneliness of being outcast. Mr. Pignati, being random, is another key aspect of the story because it hints the two teens are not quite as rebellious as one might imagine. It would be easier to pick a student from school for example, but by picking a random person they decrease the risk of an authority figure catching them. This indicates they are exited by the rebelliousness of the action, but still scared of the consequences.