I'm in a public place, like a school. I go into a large bathroom, where there is a conventional 'throne', and beside it, some sort of mechanical toilet contraption, with a lot of robot arms and other attachments.

There's a bit of sewage seeping around the bowl of the mechanical one, but when I flush the conventional toilet, the mechanical one starts bubbling up and spewing thick green filth. It keeps pumping it out until the room is entirely full about a foot deep. I don't notice any smell.

I wade through the sewage to the door. I'm aware that if I open the door it will spill out, so I open it as quickly as I can, step out, and then close the door again. Some of the guck runs out into a puddle on the floor in front of the door, but it seems the damage is limited.

I go looking for somebody to address the problem, and find a worker at the place. We go back to see the damage, but all the goop has disappeared. Back in the bathroom, everything looks clean and normal. "I guess the only evidence is my own claim", I say, acknowledging that I must have been wrong about what happened.