Several.

1. Sitting at my Middle Fork American River (near Auburn, California) campsite reading a book in early evening, suddenly there are 5 or 6 rapid fire gunshots. A few seconds later two teenage girls sprinted toward me with panicked looks on their faces yelling "HE'S SHOOTING AT US! HE'S SHOOTING AT US!" I bolted out of my chair and grabbed my keys, fumbling with them to get my truck unlocked so I can get myself and the girls out of there. As soon as I got the door open, by pure coincidence, two rangers pulled into the campground on a routine check (this was a primitive camp with no rangers or camp hosts stationed there). We flagged them down and later they apprehended the shooter. He turned out to be a drunk camper firing wildly at nothing in particular from a nearby campsite. He was carted off to jail without incident.

2. At the end of a week-long wilderness rafting trip in northeast Oregon, we returned to the put-in for a final night of camping before heading home. While setting up our tents on a warm summer evening, suddenly we heard thunder. Within minutes we were in the midst of 50-mph winds, torrential rain and lightning. We all scrambled inside our tents and tried to hold the tent poles in place as the wind tried to flatten our tents. In ten minutes it was all over. Two graphite tent poles had been snapped in half and my rain fly was caught in some trees a hundred yards away. Everything was soaked. Many trees were downed in the area, and branches were scattered everywhere. I was very thankful we had set up our tents out in an open grassy area. We ended up in a motel that night.

3. A bit off topic since this wasn't actually during a camping trip, but it is bike-related. I was driving to a friend's house in Idaho prior to a tour on the Coeur d' Alene trail. As I drove into a strong thunderstorm on a rural deserted two-lane highway, my bike rack broke and my bike hit the ground at 65 mph, but was held to the back of the car by a cable lock. I pulled over and spent the next half hour trying to repair the rack while lightning repeatedly struck the ground on both sides of me, within a quarter mile. I kept running back inside the car and trying to wait out the storm but it wasn't moving on fast enough, so I'd venture out again hoping to get the bike secured enough to at least drive out of the storm. Probably not the smartest thing I ever did. Luckily, I finally got out of there unscathed. Scared the snot out of me though. The bike was fine other than both wheels bent up and one pedal destroyed. One wheel was able to be trued, the other had to be replaced.