I have been a passenger in a C-170 with a STOL kit that flew backwards over a beach on the Washington coast. We landed well behind where we took off. The takeoff and landing were both nearly vertical. Had a steady wind from the ocean.
You forgot to unfurl the course sails and get out and push.
Was that intentional or unintentional?
Intentional. The pilot was very good at it and his airplane, a highly-modified 170, had exceptional performance.
I'm sure it's happened a few times with unsecured planes in a windstorm.
It would be a neat trick to see a pilot pull that off intentionally and under control.