Haha, I have an good story about this...
My senior year I went to math completely burnt after lunch, and my teacher was one of those younger dudes who was pretty cool... told drinking stories and stuff, funny as hell, but he could definitely be a hardass. So I'm sitting there, several people have told me I reek, and some kids behind me realized I was high and tried to mess with my head. I thought it was pretty funny, so I started laughing hysterically and the teacher approaches me...
"Andrew... so what are you laughing about?"
"Nothing..."
"Yeah. I'll bet nothing..."
Then he just gave me a weird glare and stalked off.
I never felt so sick to my stomach for the entire remaining hour of that class...