The inabilility of those with XY (male) chromosomes to see anything that is clearly in sight. They require a XX (female) chromosome member of the population to guide their eyes to the item within plain view.
Him (while peering inside the refridgerator): Honey, I can't find the mustard.
Her: Stop manlooking. It's right there, behind the milk.
Him: Oh yes, now I see it, there it is.