I have seen and been involved with some tail-sitter incidents. First was a most unlikely one, a USAF RC-121 (L-1049 radar Connie). It had come into LANY at then KIDL for the ALRI modification. This involved stripping the cabin radar consoles and equipment out. A midnight shift techie started disconnecting things and hauling them back to the rear door. He was diligent and found on his last trip to the door that it was now very much downhill. It was the only Connie I ever saw on its tail.
The DC-4 (C-54) was tail tender and the tail post was always used during loading. On going to remove it one night we were unable to get it out. It was firmly planted and obviously the aircraft was misloaded. But no, they knew better and had a towbar and tug attached and the aircraft moved forward to "free the tailpost". Down came the tail end but only partially. The towbar was short, the tug heavy and the A/C was held in a suspended position, the tail skid not touching. All we mechanics could do was laugh. I saw more that one aircraft takeoff with tailpost still dangling and a few quick returns from taxi0out for departure whan another aircraft informed them that their tailpost was still affixed.
Greatest sight of course was a B747 on its tail. One night at Eastern, the brain-dead midnight shift mechanic who was to raise the flaps after an inspection opted to raise the wheel-shaped handle instead of the moving the airfoil shaped one. It was an amazing sight, looking like a rocket being raised for launch.