This one has already been submitted, but I feel that it needs to be resubmitted with the following fact:
When this chapter of the manga originally came out, The Sixth Sense was just airing in Japanese theaters. With Araki being big into western media he had already seen it, but most of Japan had not.
Jolyne didn’t just spoil the movie for the people watching it in the manga, she spoiled it for every JoJo’s Bizarre Adventure reader who had yet to go see it. Which would have been god knows how many people.