“No, that’s just your dad sleeping with his eyes open.”
[Additional line for comic relief]
“Then why is he eating the dogs brain?”
Let’s be frank. You can’t sleep with your eyes open because it looks like you’re about to eat brains.
You know those eyelids you’ve got?
Cool, but don't do this every day.
Not only will you look like a zombie if you don’t but you will probably also get really dry eyes and feel bad so instead just shut them and keep them shut. In the old west the whole “sleep with one eye open” made sense but not in the modern world. So keep them shut… or as the movie… Keep your Eyes Wide Shut… and you are considered “normal”.