I think of dressing up on Pirate Night the same way several of my seminary professors talked about confession in the Episcopal Church: None must. All may. Some should.
And I still chuckle thinking about another all-adult family on the same cruise we were on our first. We had been hanging out in the concierge lounge (my dad chose to book concierge...and yes, we have all cruised as "commoners" since and love it just as much) with the other family (maybe the meet and greet time??) where the father was all out and the mother was in process of getting all out. Their daughter - who looked to be around my sister and my age - was shaking her head and rolling her eyes at the fuss they were making. She wasn't planning on any dressing up (we were just doing something with the little bandanas ourselves). Well, a little later when my sister and I were heading to the lounge for drinks, the daughter was in the hall being laced into the corset of a dress by her mother. She looked at us and mouthed "Save. Me." We just shook our heads in sympathy. Hee hee!