Not Merely a Metaphor
Chief Master Sergeant Walter Harriman shuffled blearily into the commissary, feeling at least three-quarters asleep. Needing something easy to eat in his diminished capacity, he almost sleepwalked towards a fruit bowl and clumsily grabbed at an apple. What he really needed was coffee, but he needed to be a little more awake to be able to drink without spilling it.
He headed unsteadily to the exit of the commissary, shaking his head to clear some of the cobwebs. As he raised the red fruit to his mouth, his eyes told him something was wrong. Several blinks later, he realised that an earthworm had beat him to the first bite. This meant something important, he was certain of it.
Gears began to turn in Walter's head, but not necessarily the right ones. His sleepy synapses made convoluted connections, leading to a conclusion which only seemed logical at 0-dark-hundred. Something clicked, and a light labelled 'panic' lit up in his head.
And that was why everyone in the commissary that morning heard Walter spontaneously yell, "Unauthorised incoming wormhole!"