Off and on, on and off

Sometimes off means on and on means off.
What’s up or down with that?!

You can say “the siren went off.” What you mean is that the siren turned on—it was going, it was blaring. It wasn’t off at all.

You can tell someone to “turn the light off.” But at the same time, you could tell someone “The light went off.” And what you mean is that the light started blinking or it turned on. It wasn’t off at all.

My fire alarm went off this morning as I was getting out the shower. I mean to say that it turned on...it started REEEP REEEEP REEEEEEEPing as I tried to shut it off as soon as possible so as not to bother the neighbors. And for crying out loud, there was no smoke anyways! Why was it on?

Sometimes I wish my brain would go off. Or on.