Cats are terrified of cucumbers and bananas and no one knows exactly why. People on the internet have been placing cucumbers, bananas, and various objects behind their unfortunate pets while they eat and filming the response. Dr Roger Mugford, a specialist in animal behaviour, said: "I think that the reaction is due to the novelty and unexpectedness of finding an unusual object secretly placed whilst their heads were down in the food bowl."Cats have to be suspicious of the unknown: it could represent the danger of a snake or another predator. I suspect that there would be the same reaction to a model spider, a plastic fish or a human face mask. "So not an inherent feature of cucumbers, just their unusual context." a cat has an adverse reaction and retreats from a banana, it is more likely that they are reacting to the smell of chemicals in the banana's outer skin.
Many cats also dislike citrus smells and will avoid citrus fruits. if your cat fears bananas or cucumbers, it is probably because someone had been chasing him with one, much as you might retreat from a nut case with a bucket of sewage.