I do think it's bad, often, but I don't think it's obvious why. I think that the answer requires a lot of specific historical knowledge about the political role of the police in the United States, and the recurring real abuses of police power. If you asked Robert Morris whether computer professionals should respect people's privacy, I bet he'd say yes, sincerely. I propose to take this claim seriously. It's not that one is always okay and the other always not okay, but the standards are different.
Practical jokes are about trust and testing trust.
It's unlikely that a teacher of graduate students would think to raise it. I believe it is a serious problem in our society that adolescence commonly lasts into the mid-20s and beyond. The reasons have to do with a lack of serious adult values, the commercial glorification of youth, a tight economy in which adult life often truly is bleak and joyless, state-sponsored lotteries, and many other things. Professional ethics classes, though, do not address this problem. The model for professional ethics courses is medical ethics courses.