Cake

The Cake is an item sent to Henry Stickmin at the start of Escaping the Prison.

Role
The cake contains one of six hidden objects that Henry can use to try and escape the West Mesa Penitentiary, kicking off the plot of the game. The object in the "cake" can be either: a File, a Rocket Launcher, the NrG Drink, a Cellphone, a Drill and the Teleporter.

In Completing the Mission, during the “Multiverse Correction” secret ending, it was revealed that the Center for Chaos Containment sent Henry the cake to fix an anomaly in the multiverse.

Trivia
In the |The Developer Commentary for Henry Stickmin, Puffballs states that the idea of the cake is that it is supposed to have one of the six items inside when you choose, not to have them all inside the cake at the same time.