Nozzle for a pressure washer. Flat sides on the back seem to indicate you can use a wrench to tight it on something, like a hose or fitting.

Osha always talks about how its not the first mistake that kills you, and I think in the case of home electrical, leaving a panel energized while your hands are in it, would count as number 1.

Firefox has an HTTPS-Only mode. Did you double check that? Make sure you can get anywhere on http tcp/80 in the browser.