Any good fisherman knows that bananas equal bad fishing mojo.
Express your luck or misfortune during your last fishing. boating or sailing excursion with BananaFish and No Bad Day Fishing tees, stickers and flags. Fly a No Bad Day Fishing flag on your boat when the fishing has been good. Wear a BananaFish tee shirt if you had a bad luck day. LINK
No Bananas Fishing Charters also lays out some various theories as to how and why the superstition got started.
Some say that bananas give you the runs so you are always in the marine head and can't catch fish because you are busy "draining the pipes". LINK