I've been flying a lot for most of my life, thankfully my parents can afford it, so I've had quite a few unpleasant experiences.
One time I was terribly sick on the flight, so the landing was like hell to me, I thought my ears, nose and head would burst at any moment.
Another time during a flight from Toronto to Moscow some dude got completely wasted, was apparently sexually harassing some of the stewardesses and passengers, so we made an impromptu landing in Iceland to hand him over to the police.
Yet another time I think I was a bit sick on the plane, and when I went to the bathroom, while waiting for the occupant to get out, I fainted for a few seconds, which was more than enough for me to collapse. When I came to a few seconds later, the staff were just standing there, while I was passed out on the ground. :/
About a year ago I was returning with my mum from a skiing trip in France through Geneva, but for whatever reason we got held up in Geneva for like 8 hours. We rather rarely do transfers, so being held up for that long was a first for me, but it turned out better than expected, we just left the airport for a while, grabbed a taxi to Lake Geneva and enjoyed our time there.
Edit: Oh, I forgot the reason I was telling this story.Since the registration wasn't opening until a few hours before the flight, we left our luggage at a storage room. When we went there in the evening to get our bags... it was closed. After running around frantically, at one point a janitor went in and we pleaded him to give us our bags. Thankfully he was a nice guy, and we managed to leave Geneva without any further incidents.
Another story that isn't exactly about planes, but about 6 years ago, we flew to Switzerland for a skiing trip, and the next day we got a call from my grandma, who was and still is living in Germany that my grandfather had passed away... Needless to say we took the first train there.