Am I being unreasonable?
So, my first time DMing is coming up. I have let my players know that, since it's my first time DMing, we're doing something relatively simple; it's going to take place in a maze-like dungeon. I'm really excited, I've got a poster board with Velcro tape and felt passageways I'll put on to reveal different areas, etc. I let my players create their characters and pick a "crime" since that's why they're being thrown in here, as punishment. One player in particular decided to become a rock eater from a movie. I knew immediately he wanted to try to eat his way out of the maze. I've warned him already the entire campaign is taking place in the maze. That's it. There's no ifs, ands or buts about it. But he has made comments like, "we'll see", etc. Would it be unreasonable if he tries something to literally just say, "nope. It doesn't work, the magic keeping you in prevents it." I don't want to be a bad dm, but I also know this guy. He will do everything in his power to be a problem, but he's the brother of my best friend, so I don't really know what else to do...