NINETY NINE LIVES (TESTED)
When you are at the drill part of cavern catastrophe die after you get the check point box. Then turn the camera back and you'll see a few of boxes. Smash them with cortex's head (pressing circle). Then throw cortex with square and circle and all the way to the drill. When cortex returns he will fall down and you'll start again from the check point. The boxes are back!!! Repeat this until you get ninety nine lives!!!
NOTE: You can also throw cortex with x and circle but make sure he falls in the hole.
Added by: Jimmys Apr 3rd 2012, ID#33984