Rubik's Revenge was the brain-teaser to end all brain-teaser puzzles. As if 9 squares per side wasn't hard enough, Rubik's Revenge had 16 squares on each side which multiplied the complexity enormously.
If you couldn't figure it out, you could always peel off the stickers or pull it apart with pliers though!
Do You Remember Rubik's Revenge?
Do You Remember Rubik's Revenge?