Why do we say that an alarm clock goes ‘off’ when it actually tuns on?

my non native english ass just had a stroke reading this   reply

We say an that an alarm clock goes off because it was already turned on. When you set an alarm you turn it on, when it goes off you have to reset it later. hope this makes sense   reply

It!s the same reason we say a volcano goes off when it explodes or a person goes off when they start yelling. It’s just a way to describe something loud and annoying. Kind of like how we say it’s raining cats and dogs to describe heavy rain, you just don’t take it so literally (called an idiom)   reply

why do u tell a kween to go off; SHE ALSO TURNS ON ╮(￣▽￣)╭   reply