Hello, I'm translating a text in which two men are looking for a mysterious item which is part of a list. They have no idea of what it is or what it looks like, and therefore, they start having an argument. The first man tells the other : I'm fairly sure the thing is your pigeon, anyway. I was thinking of something such as : De toute façon, je suis quasi certain que cette chose est sous votre responsabilité. The thing is I can't think of something that would be as informal as "your pigeon". Ideas anyone? Thanks a lot!