I’d got so used to hallucinations I completely forgot the lines on the road were moving about and that the sky was constantly changing colour. Just kind of accepted that these things were happening after a few hours.
Me: Can I use the bathroom? Teacher: I don't know, can you? Me: When I was using "can" I was using its secondary model form as a verbal modifier asking for permission, as opposed to expressing an ability. I thought since you were a teacher you'd know that. My bad. MAY I use the restroom?
May is clearly the correct verb to use, instead of using an ambiguous form of can. Don’t try to be clever, just make sense.