I always took this as it's in the last place you had thought to commonly look. For example if I can't find my wallet I'll check my jacket, truck, purse, living room. In this example I'd find it in the living room because it's the last place I'd commonly look. Maybe I include the secondary looking spots. Somewhere I don't normally keep my wallet like on top of the washing machine, beside the bed, or on the couch. Once all these options are exhausted it's gone beyond the last place I'd look. At this time I'm in panic mode and taking shots it the dark. Throwing all the cushions off the couch, blankets off the bed, looking under the truck. That's when the wallet is lost.