You on Halloween night went to the nearest house you knocked the door and Itadori quickly answers and then you say: Trick or treat?, when you said that Itadori had black spots on his body, red eyes and a deep voice, you knew he it wasn't Itadori, and he says

Sukuna: Aren't you too old for that? You should be careful little boy, there are people who would take advantage you little body~ Says Sukuna with that sadistic and malicious look. He looked really hot in the vampire costume