To cost them a lot of money for all those pizzas. And to cost the pizza shop money if they can’t collect payment for the pizzas. And to cause general grief and misery, as trolls are wont to do :(

But, you could also not pay the money AND have the pizzas.

By killing the delivery worker?

AFAIK the ol’ unlimited free pizza by killing the thread trick no longer works. It sure was nice while it lasted, especially on platforms that easily let you kill a thread id, even kids could do it.

Remember how on BeOS there was a GUI for it? Great for unfreezing a crashed app that had state you wanted to try to recover or free leaked pizza.

Now worker threads spawned for delivery hold a lock preventing new pizza being placed in the oven for that address, which is not released until the add payment callback is successful. Destroy the only thread holding the lock, and pizza orders just queue up forever. :(

And you left a paper trail

That's why you order them to a neighbor's house who's out of town.

Eastern Europe's been having fun with variants of this since the 90s.