DK64: GameShark + Autosaving = Bad 

Back in the past when I was a dumb kid, I used GameShark on my DK64 cart. Unfortunately for me, DK64 likes to autosave every 2 seconds, and has no "erase all" feature.
I forget what codes I used, but whatever they were, they caused Donkey Kong to get fucked up. No one else. Just Donkey Kong.
The DK Rap and the Bongos are the only things I've found that are changed.