When I was in the Navy, single, and high spirited, I would take any opportunity I could to fly very low, just off the "deck". The deck in this particular situation was the desert in remote Nevada. I was flying very low at 600 mph. Low being if you were standing up as I flew by, you wouldn't be after I flew over and would have been smart to get out of harm's way before I got there. The adrenalin rush is pretty intoxicating. The spike in apprehension was pretty riveting when I hear an unexpected thump and felt the aircraft shutter!!! I jumped away from the ground - engine was still running smoothly, flight controls still steady and responding!! Soooo, I didn't say anything, watched every gauge like a hawk, and headed straight back to the base in California. When I landed, I climbed out the jet and check the belly for scrapes, leaves, trigs, etc but found no evidence that I tied the guy(s) that had flown the lowest … nor did I test that boundary from then on.