For untrained folks (untrained in eating so much fruit at once) it could stress the liver as fructose can only be processed in the liver. 30-50 grams of fructose is what usually the liver can handle at a time. So eating more than 8-10 bananas at one sitting might not be the best for your liver.
Also a research have shown that different people are more efficient at metabolizing fat or protein or fruits or grains. So just because Freely the banana girl eats 50 bananas a day or Dean Karnazes eats pizza and burgers on his runs doesn't mean I anyone can get away with it