What were some frightening non-combat experiences in a war zone?

Being in a war zone can be frightening. My three scariest incidents from Viet Nam were were not in combat:
1) I was the FNG at Bunard when there was a huge boom -- violently shaking the teamhouse. I was leaning back in my chair with my head against the wall and it felt I had had just been hit with a sledge hammer. I hit the deck, fearing for my life. My teammates nonchalantly walked out laughing their butts off. WTF? I joined them only to see an F4 Phantom (I'm guessing) buzzing our camp. A sonic boom can mess with your mind when they happen at point plank range. I'm the little kid in the picture wearing a T-shirt and shorts. (hardly "green beret" material -- LOL)
2) A few months later I was relaxing and enjoying the show from a hill as a battle was taking place down the hill from me at Song Be. I was a safe distance away when all hell broke loose slightly above and behind me. It was a Cobra Gunship. I never heard that whispering death sneak up on me. It was firing rockets at the bad guys below.
3) I was alone in a hotel room in Vung Tau with some Communist out on the veranda yelling, "F.U." at me. Believing the best defense in a strong offense I burst through the double doors with my M3 Grease Gun ready to set things right -- only to have a Communist Tokay gecko hanging on the wall stare down at me and repeat, "F.U." It was lucky I already ate or it would have been my dinner for scaring me so.
These incidents only lasted seconds, but were more frightening at the time than the two times I was wounded and alone.