Not in the sense that they would become yellow and unzippable or fly around in a cape. However, if someone ate masses of bananas over a long period of time then died, you would be able to tell that they had in an autopsy from the amount of potassium and the balance of other minerals in their fingernails. So, in some senses, if they eat a lot of bananas they will take on certain banana-like properties.
What's the worst weather you've ever been caught in?