I've had a few occasions when I haven't been happy in a plane.
Latest was in 2004 when I came back from amsterdam, our pilot informs us that a landing gear won't deploy.. so we circled the airport for a good 45 minutes, but landed safely and I'd assume they fixed the problem
Once I was flying to the cayman islands our plane landed and took off like 4 times, that's fucking horrible.. really.
When I was like 10 and we were in New York, we took a Jumbo jet to LA, and after lift off the plane immediately turned like 45 degrees or more, and it looked like the wing would hit the ground (we were probably hundreds of feet in the air, but the sensation was enough to have me remember it until this day)