I'd love to do that. The easiest way is to talk to DCs, I'd love to do that in reality. On some occasions I have induced auditory hallucinations (they were not all that pleasurable) but only kind of accidentally, but you're on about just conversing with a voice in your head...

I once did this while going to sleep, you know sometimes you start to hear voices, and this way I've had conversations, but they make NO sense. It's fun but that's the only time I can do it and there's no guarantee I'll be conscious at that point or for that matter reach it in the first place.