Was in Atlanta for several days where my brother and I rode the Alpharetta Greenway Trail, a very unusual trail in that about 60% of it is wood constructed and elevated along a river course. For multiples of reasons, including very slick wood decking when wet, there is a 15 mph speed limit. This is no problem for 98% of the people on this trail. Other than my bike, I saw only two other road bikes. No problem for us either since my brother is a 13-14 mph rider.
At one point in the ride, in my mirror I saw a bike closing rapidly while weaving maniacally through the walkers and runners. As he came up on us as we were in a fairly sharp curve, he tried to dart to the inside directly into the path of a family group of bikers. It quickly became obvious that a head on was in the cards but he locked it down and somehow didn't wreck or hit anyone. 100 yards further down and he blasted past ringing some little dorky bell as, I assume, a warning to us to stay clear. When my brother and I got to the end of the trail, we saw him; an Oriental guy dressed like the guys in the movie Road Warrior, in black with a scarf covering his face except the eyes. This trail is only 6 miles long so my brother and I immediately turned around and headed back with the road warrior still sitting at the trail head. As we got back to the far end I was in the process of dismounting before getting to the loose gravel walkway back to the parking lot when here comes the road warrior again doing a hard and rapid turn around me (bell ringing). That worked just fine until he got to the gravel, at which point he was still in a hard turn at maybe 15-18 mph. You can guess how long it was before he dumped and hard, about 1/10th of a second. I have no idea what on earth he thought he was doing.
At first, I was worried because he was on the ground bleeding and groaning. We went over, looked him over and helped him up but after a couple of minutes it became apparent that his physical injuries were superficial, but the loss of face involved was significant. Afterwards, my brother and I admitted that the experience was the highlight of the day.