We backed into our site and fell through the septic tank.
We were volunteering on a ranch in Oregon and years ago a caretaker of this 10,000 acre ranch had a mobile home on that site. The rancher who directed us where to park was unaware that there was a septic system there. The left rear of the motorhome dropped in. It took two days of ranch hands building a ramp under us so we could drive out. In the meantime, we slept in a very uncomfortable heavily-slanted position thinking we could fall deeper at any time. Amazingly, nothing was damaged on the motorhome.
It was funny..... afterward!