From the story of the little girl who said "I know how to spell "banana", but I don't know when to stop". Not knowing where or when to bring a production to a close (compare fencepost error). One may say "there is a banana problem" of an algorithm with poorly defined or incorrect termination conditions, or in discussing the evolution of a design that may be succumbing to featuritis (see also creeping elegance, creeping featuritis).
HAKMEM item 176 describes a banana problem in a Dissociated Press implementation. Also, see one-banana problem for a superficially similar but unrelated usage.