Source : Free On-Line Dictionary of Computing

one-banana problem
     
        At mainframe shops, where the computers have operators for
        routine administrivia, the programmers and hardware people
        tend to look down on the operators and claim that a trained
        monkey could do their job.  It is frequently observed that the
        incentives that would be offered said monkeys can be used as a
        scale to describe the difficulty of a task.  A one-banana
        problem is simple; hence, "It's only a one-banana job at the
        most; what's taking them so long?"
     
        At IBM, folklore divides the world into one-, two-, and
        three-banana problems.  Other cultures have different
        hierarchies and may divide them more finely; at ICL, for
        example, five grapes (a bunch) equals a banana.  Their upper
        limit for the in-house {sysape}s is said to be two bananas and
        three grapes (another source claims it's three bananas and one
        grape, but observes "However, this is subject to local
        variations, cosmic rays and ISO").  At a complication level
        any higher than that, one asks the manufacturers to send
        someone around to check things.
     
        See also {Infinite-Monkey Theorem}.
     
        [{Jargon File}]