Someone tried to gaslight me not long ago but the attempt was so obvious I saw right through it.
We were driving around the city having an argument and then they couldn't find their pack of cigarettes and accused me of throwing it out the window. I knew I hadn't but they said they saw me do it. Then started to use that an excuse to verbally abuse and harass me.
A little bit later the pack of cigarettes magically turned up again. They accused me of hiding it just to mess with them.
I knew I had done neither of those things.
Other cases its much less obvious and its a horrible feeling of having your sense of reality messed with. It has happened to me where I just feel confused like "What the eff just happened?! Am I losing my mind?!" After lots of introspection I concluded I was probably being gaslighted.... Although if you can't "prove" it, the sense of confusion and disorientation doesn't fully go away for a long time.
Being gaslighted is one of the worse things IMO.
I agree with Purple, you can't "unintentionally" gaslight someone. Its usually done on purpose.