Jack Tylner (Also known as Hooknosed Jack) is one of the Rat Pits owners you have to visit in Rat Catchers. He is located just outside of the Varrock Rat Pits along with his cat Pox. If you are not currently on "Rat Catchers", he will simply say "What?", then, "Actually, I don't have time for this," when spoken to.
When talked to during Rat Catchers, your character stares at his nose, and then says it doesn't matter when Jack notices.