The last call
No one likes getting random soliciting calls from private people and companies offering you products or services you’re not interested in, and the worst part about those calls is that no matter how many times you politely turn them down, they won’t stop calling, until the point where it becomes a nuisance, and you’re afraid to pick up the phone.
This person decided to give them a taste of their own medicine, and put the phone number that keeps calling him on different random advertisements. Now, they might get random calls from people interested in adopting monkeys, buying used cars or receiving different, strange services – see how they like that.