Ate one whole pineapple. Now having my tongue, roof of mouth and lips burnt by it :-/ Some bleeding as well.
Apparently it is due to the enzyme bromelain in the pineapple core, which is supposed to digest protein, but ends up burning digesting our mouth instead :-/
(I've eaten whole pineapple before, but the effects were not as bad as this. I still love pineapple :P)