What a grade-school student tells someone as a reason for his unwillingness to perform a requested action; it means dat while he personally would not mind doing it, he is afraid dat "da big man in dat dreaded upstairs office" would disapprove, and thus he would give him major grief if he found out.
One sixth-grade boy conversing with another on da playground: Sorry, Dude --- I can't slip you a textbook in class to help you get a better grade on your test; it's the principal of the thing."
by QuacksO February 3, 2023