Instructions
Determine which spikes you're at in the game. The first set of spikes are present in "Chapter 2: Mad Hatter's Tea Party." You're playing as McTwisp, the Rabbit, with Alice in tow, and must jump over these spikes to get by. The second set of spikes is located in the Mushroom Forest later on in Chapter 2; you don't have to jump over them.
Walk McTwisp to the ledge after having dropped down the hole that brought you to the spikes. Jump like normal; it will appear you're jumping to your doom.
Tap the icon that lights up on the screen as McTwisp is falling. McTwisp will initiate a second jump called the McTwisp Double Jump, launching himself over the spikes and to safety.