maybe knife

That knife you use after making a sandwich and place on the edge of the sink because you might decide to make another sandwich

"Why is it that everytime I go into the kitchen there's a knife just sitting on the edge of the sink? Why can't you just put it IN the sink?"
"That's the maybe knife, because maybe I'll make another sandwich, maybe I won't. But I don't want to dirty up another one if I might make another in forty-five minutes."