The brain puzzle in the Necrotic Laboratory is really not designed for a controller. And the game doesn't tell you how to enter free cursor mode (it's L3, by the way).
What's the context for the line about eating dirt? Because it sounds more like a line from some TV cartoon that looks like that drawing than something from a AAA game.
I think it's Karlach IIRC. Whenever you tell one of your team mates to stay at camp they'll say something grouchy. Karlach's something along the lines of "I'll be here, eating dirt or something."