Here is how my last interview went:
"What is your biggest weakness?"
"Well, I am usually incredibly detailed oriented, but sometimes they find a body."
"I beg your pardon?"
"Well, what I mean to say is that I am very diligent in wrapping up loose ends at the end of an assignment, but occasionally I let a small detail slip that comes back to haunt me. Fortunately, I am very good at covering my ass and I make sure that someone else's DNA is always left at the scene. If you want to make sure it's never your DNA, I suggest hiring me as your wisest course of action."
I got the job!