Play as Ronald McDonald:
After beating the game with 120 stars, go to the Hazy Maze Cave level and on the title screen where you select a star ranging from 1 to 6, press A,A,Z,B,B,A,Z,A,B in the logical order, and select the first star for the level. If you did this correctly, you should hear Ronald McDonald laugh before the level begins. Go to the hazy maze part of the level and keep walking around until you see Ronald McDonald chewing on the tip of one of his big red shoes and laughing. DO NOT GET CLOSE TO HIM!!! If you get to close then he will run away and you can never get him. So at a safe distance, do a backflip, and while Mario does his backflip rotate the joystick clockwise four times, and then rip the joystick out of the controller. If done correctly, Mario should land on his head and black out. At that, Ronald McDonald will approach Mario and start shoving hamburgers in his mouth. This will kill Mario and you will never get to play as him again, but you now get to play as Ronald McDonald!!!
BONUS: If you beat the last Bowser and save the Princess something different will happen. When Peach suggests that everybody bakes a cake for Ronald, he will take off one of his shoes and start to beat Princess Peach with it. The two toads will get scared and jump off of the bridge into the moat and drown. Ronald then laughs and says, "No cake for me! Just hamburgers!" Then the Hamburgler will jump out of the stained-glass window and start dancing with Ronald as the two eat hamburgers. Then the game will explode killing you if you don't have the proper protection.