Well, because DPDR is a psychological abstraction, there really is no “it” to talk about, and when you look around this site and elsewhere, the language people use to talk about their experience is very different from person to person. Moreover, this is a very difficult condition to describe to anyone who hasn’t really experienced it chronically (though most people do have brief glimpses of it at some point in their lives).
I’ve found that the best description that matches my own experience, and perhaps one that others might be able to conceptualize, is the idea that DPDR is like living life in “first-person” mode. It’s a video game reference, obviously. But if you’ve ever played a first-person shooter or are just aware of such games, it’s a lot like that. The environment around you, although it might be 3D modeled, is nevertheless projected on a 2-dimensional screen. You are observing the scene in front of you while feeling you’re not truly a part of the action. When you move, it doesn’t feel like normal person movements, it feels more like you’re floating around and the environment around you is just changing to match the player’s controls. And you know how if your character is brandishing a weapon, it just seems like the weapon is not really attached to him, but just protrudes out from the bottom of the screen?? Yeah, my body parts just look and feel kind of like that, as if they are just protruding out from my otherwise disembodied consciousness.
I think that description—assuming your interlocutor doesn’t just assume that you are a priori insane—might be perhaps the best way to get somebody who doesn’t have it to perhaps get a reasonable understanding of what it might be like.