The private pilot in a light, single-engine airplane was taxiing toward the runway. The pilot observed a four-engine military C-130 that appeared to be doing an engine run-up, about 300 feet to the left of his taxiway. Seeing the implications of this setup, the pilot asked ground control for further taxi instructions. The controller cleared him to proceed behind the C-130 at his discretion. The pilot continued to taxi behind the C-130 and the plane subsequently blew sideways and overturned.