From Jack Kerouac's On the Road
Through halos and rolls and gold foals that were like the existence of the gleaming spear in His right hand which sayeth c’mon boy, go thou across the ground. Go moan for man. Go moan. Go groan. Go groan alone. Go roll your bones. Alone. Go thou and be little beneath my sight. Go thou and be minutest seed in the pod. Go thou go thou – die hence, and if this world report you well and truly.
It can be inferred from the text that Kerouac probably uses it to mean "Go!" but where did it come form?