Funny that this topic came up, I had been meaning to post a similar experience for some time!
Flying AA on JFK-SFO, I can't recall if pilots had come on the PA to tell FAs to prepare for landing, but regardless, FA were picking up the remaining plates/glasses from passengers seats. My personal tray table was still out with the table cloth and glasses, when boom the plane jolted, as if we had hit turbulence. The flight attendant then bent down to look out the window, as did I, and to her and most everyone's surprise, we had landed! To this day, I still don't understand how its possible that we could have landed with service items still on trays and passengers/flight attendants not seated and buckled in. All the FA's and passengers started looking around at each other, like ... just happened?!