Pendejo is a vulgar Spanish-language term of abuse. To call a person a pendejo is essentially to call him stupid, although it also carries implications of wilful stubbornness and rank ineptitude.
A toilet may run periodically due to a problem with the flapper, the flapper seal, the flapper chain or a high float.
If the water refill valve on your toilet suddenly switches on after a period of inactivity, it can give the spooky impression of a ghost flushing the toilet, especially when it happens late at night. The cause of ghost, or phantom, flushing is easy to understand, and prevention is a straightforward maintenance issue.