Absolutely!
We just got back from the Wonder 4 night and yes, there was pirate night - and for the first time - fireworks!
It was a blast. You don't have to do anything. Most people just wear the bandanas given to you at dinner. We brought an eye patch for my DD and she enjoyed that. Some go all out - and they look great - but not many.
You'll get a pirate map for your menu that you can take home.
The party goes late, so I made sure my DD got a nap. It was a fun night - and there's a late night buffet with lots of pirate food, as well.