Ghoul School

Invincibility:
Collect the Spring Shoes and Towel, then go outside of the gym. Equip the Spring Shoes and Towel, enter a locker, and hold Up. Enter the "Equip" screen, and equip the Shoes and Bat. When game play is resumed, your character will remain in the locker, but may move freely. Although enemies may be attacked, your character will be invincible. Note: Falling will still be harmful.

Bonus room:
Collect the Spinal Zap and gain access to the elevator. Enter the elevator from the first floor and push "Up". Push "Down" when the indicator arrow is between "1" and "2". Repeat this until the indicator arrow remains between the first and second floors to enter room "00".

Hint: Access elevator:
Kill Spine Tingler with either the Gamma Gun (recommended) or Deweytron to gain access to the elevator. Note: You can also use the weapons listed above to easily destroy Admiral Aorta and King Cornea (the Ghoul Master).
Information in this section was contributed by Stinkytaco.

Hint: Getting through Hall #24:
In Hall #24 you will be confronted by three very fast moving monsters. There are three ways to get by them. The first is to move through the hall as slowly as possible. When the monster appears on screen, keep firing the Dewetron and you should kill it. Note: This requires a controller with a turbo feature. The second way is to enable the "Incivility" code and rush through the hall. The third way is to go to the principal's office and reach the room with the music the same as Hall #24. You will know it is the same music because its the only room in that section that has music. When you get in the room, find the clock that has the hands moving wildly. Smash the clock with the bat and the music will stop. Ths will also get rid of the music in Hall #24, and it will also get rid of the monsters. Note: By smashing the clock you will get 1,000 points.
Information in this section was contributed by Stinkytaco.