This is a glitch in Super Paper Mario that makes Luigi have a seizure. First, go to the Underwhere. Then, you go to the room where the orange water fountains are in motion (moving up and down). After that, jump on it and get to the edge as close as you can (before you fall off). Now, try doing the super jump. Luigi will start spazzing out, as if in an earthquake, or as if having a seizure.
Note: this is really frustrating and may take a few tries.
Discovered by MP3GK