What are you even on about? [He's not going to ask someone about a god that he doesn't even know the name of?]

You can curse objects too, I think. Put bad luck on them or make them cause misfortune. I've heard about stuff like that from other pirates.

Pretty sure the downside of Devil Fruits count as a curse, right? [Unless Luffy enjoys the constant threat of death by seawater that plagues their lives.]