You take the fork with both hands and raise it up above your head, dismissing the urge to yell, "you shall not pass!" You then plunge the fork with all your might into the wall. With a muffled whumpf the fork wedges in the crack between two marshmallows.
The marshmellow walls convulse and heave with pain, but eventually settle to their original state.
Now that the task is done, you stand back and marvel at your handiwork... If there was any sun in the room you could probably use this to tell the time, or you could hang your coat on the newly fashioned coat hook.
But then you recall Macguyver saying "We are all going to die, the trick is to not rush it." So unphased by this early setback you pull the fork out of the wall and attach it to the rope. You hurl it with all your might lasso style at the ceiling and despair as another muffled whumpf reverbarates around the room.