One of my latest marinades uses pineapple. I have been using it on pork and its really tasty. Tonight I tried it out one some boneless, skinless , chicken thighs and it turned them to complete mush in about an hour! Now I know that pineapple will break down the proteins in meat (or something like that) and has the potential to do this, but I have never seen it happen so fast.
Not sure if you can tell with these pictures but the chicken pretty much fell apart when I flipped em with the tongs. They had a nice flavor but the texture was awful, really mushy.
I must have got a batch of super pineapple.