The real basics of it are King Crimson makes it so something just didn't happen. It doesn't matter weather you think you did it or not, it just didn't happen. There's more to it then that, but that's the "less then a fucking essay" explanation.
Golden Experience Requiem is way more confusing to me.

More or less, just in a more confusing way. GER makes it so the person just never wanted to do what they did in the first place. It basically goes back in time and erases the thought process that led a person to do something, so they never actually do it, but without actually going back in time, which is the confusing part.
And then you've got this fucker