Was flying out to a practice area, a guy overtaking us said he had us in sight, I saw him pass by, then shortly after he made a sharp turn right at us. Guy completely lost his SA. I was not happy.
Another one was during a night flight, I just happened to look up and see a chopper zoom right by us. No radio calls, his lights blended in real nice with city lights since he was lower. If I had to guess, we probably missed by 100' I was rather amazed I didn't have to change my underwear ofter that one.
Another was when I was first instructing and my student was having a rough day in the pattern, altitude was all over the place, kept drifting near and then away from the runway on downwind. After about an hour my patience was just about gone. We were on short final maybe 200' from the threshold, and the airspeed got 10 kts slower than it should have been, and I finally lost it and shouted: WILL YOU GET ON YOUR G-DAMMED AIRSPEED! and my student freaked and jerked the yoke back. It was one of those moments when time seemed to slow down, I grabbed the controls and landed it. We had a nice little chat when the aircraft was tied down. And I picked up smoking again at that point for a few years.