One of our former blackbelts joined a TKD class in college and basically acted like he had no idea what was going on for the entire semester. Then at the end of the semester he pulled out with some jump spin kick that knocked the dummy over, and everyone in the class wondered where the hell that came from. he explained that he took the class for an easy credit and was a 2nd dan black belt. He thought it was hillarious, And I chuckled a bit when I heard it. It isn't arrogant unless you are going in there to make the guy look foolish or something to that effect. I would take a class like that just for the credit.