"So, he did as the school instructed him to to without making a fuss about it. But underneath his robe, he was wearing his full dress uniform."
When I graduated, in the early 70's, rebellion was part of the norm (is that an oxymoron?) so people went to great efforts to dress as strangely as possible while still meeting the dress code.
One guy had a pair of slacks cut off and wore only the lower legs taped to his knees below his gown. Not me of course, I would never do such a thing.
or not. One of the guys in my graduating class wore his birthday suit under his gown, and a pair of sneakers...