In the title screen choose start/new game(don't press circle),then press
triangle, square, X, triangle, square, X, circle.
Note:you will hear a sound if the cheat is correct.
Select new game(don't press X) then press tringle,square,circle,tringle,square,circle,X.
(you will hear a sound if you press the button correctly)
Easy, die for 1000+ times. Then save your game, and load it again.
Note: Press R + square (consume lives)
You can make your Prinny commit suicide (Blow themselves up) by simply pressing [L]+[R]+[X] at the same time.
During the boss battle against Darth Moab, he will make comments before hand that are very similar to that of Darth Vader ins Star Wars.
"I halve you now"
"Do underestimate the farce"
as well as some others.
Aside from this, he also has a similar design in his character to represent Darth Vader's cape and voice.