For this achievement you have to score 15,000 points in level 4. You will be equipped with Raphael's sais and tasked with slicing pizza boxes and statues. This is believed to be the hardest level in the game but it also has the highest potential for a really high score. You do not have to hit every single object in the level but you will want to avoid the green bombs and ninja stars that appear. These obstacles can be easily avoided because before they appear a light shines on the board to signal its arrival and direction. A red light means a ninja star will come from that area and a green light warns of an incoming bomb. The stars you must not let touch your body but the bombs need only miss your weapons to avoid. These bombs and stars come from virtually the same place every time you play the level so memorizing where they come from is easy enough if you are having trouble on the first play through.
You will get a large sum of points in the final 30 seconds of the level when you are destroying pizza boxes and eating slices of pizza. each slice you manage to eat adds a huge amount to your total score.