I've always wondered why pineapple made my mouth sore, but had no idea why. This is interesting, and not what I expected! (Click on photo above)
It's worth the pain, in my opinion! In fact, there are two other things that are worth the pain, for me:
That burn you get from drinking a good soda when you're hot & thirsty, and the way Capt Crunch cereal tears up the roof of your mouth!