The Root of the Behavior
Again, this is not universal. Some dogs will just run up and snatch the banana out of your hand, that happens. For the dogs that are afraid, even though it is the majority, there really has not been a practical application of this fact. Dogs are also afraid and do not like aluminum foil, but at least in that case they have adopted a training method out of the whole thing. Bananas do not stay good long enough for you to leave them on your couch to teach your dog to stay off. They are too small to lay in a hallway and prevent passage through it, at least unless your dog is really scared of them. Really aluminum foil is the better method if you intend to use this information as any kind of training tool. That being said, it is a fun fact. Like a best friend should, use this to your advantage and feel free to have some fun with your canine companion.
It is not going to hurt them in any way, and if they do eat it, is really just a good source of potassium. However endless hilarious and adorable hours of footage has been caught of dogs reacting to bananas and foil alike. It is certainly an entertaining party trick. The similarities do not end with the cat and the cucumber. In fact, that is really where they begin. If you look into the cat with the cucumber, we find that the reason a cat reacts the way it does to a cucumber is that they believe it to be a snake. That is actually the same reason a dog will recoil from a banana. Although a snake does not typically hunt a dog or cat, the venom a snake carries is deadly to most animals, and so over the course of thousands of years, the cats and dogs who had an innate fear of snake-like things lived longer and that trait was passed down from generation to generation. The ones who did not carry this fear probably died of snake bites.
Encouraging the Behavior
Presuming the family tree your canine fell from was not afraid of snakes and still lasted through the ages, then you are in an interesting spot. Your dog is one of the few not afraid of bananas. I am still thinking about how this can help you, but really it is not very useful to you. Just passing you a soft congratulations for having a unique dog. You can probably train your dog not to react that way around bananas, but the reasons why you would want to do that are lost on me. It just does not come up often enough to be a problem and indicates no issues with your dog. In fact, it indicates they probably will not go up to a snake and mess with it, which is probably best for both of you. If your dog is afraid of bananas, using this as a punishment or training tool is not advised. Your dog will not understand that you are tossing a banana his way because he misbehaved and the lesson you are trying to impart will be lost. Aluminum foil is different in this case because the cause and effect is instant and obvious. I jumped onto the couch and the foil made me jump off.
Other Solutions and Considerations
A fear of bananas does not indicate anything wrong with your canine. It does not signify high levels of anxiety or stress, though you might tease them a bit on how high they jump when they see it. Increased exposure to bananas will likely desensitize them to bananas. This may happen naturally over time or through increased contact intentionally. That being said, there is no good reason to train them to overcome their fears of bananas. A behavioral specialist should be able to help you understand what is going on in your dogs head if they have a unique or overly negative reaction to seeing a banana, and in these situations can be addressed so that you can have a banana without them soiling the floor.