First day of classes I used to fuck with students.
Kid: "Can I go to the bathroom?
Me: "I don't know....CAN you?"
Kid: "Ugh....MAY I go to the bathroom?
Me: "I don't know.....MAY you go to the bathroom?"
Kid: "Uhh.....yes?"
Me: "Who the heck do you think you are? This is my classroom. You don't excuse yourself I excuse you."
And I'd run them around like this for a few minutes until they just got quiet, then I'd walk slowly to them and say, "I understand it's a matter of urgency that you use the facilities?"
The kid just looks up at me like "wut"
Then I just hand them the hall pass.
....keep em on their toes.