Rhapsody Adriatic Captain's Dinner

First time with RCI, sailing in October out of Venice--week long Greek Islands cruise. The other couple we are going with has never cruised before at all. We have only ever been once (to Alaska with HAL). The question of a Captain's Dinner has arisen and we aren't sure what to expect, if anything. I don't remember any such thing on our Alaska cruise, but assumed that if there was a Captain's Dinner it would be by invitation only to guests who have achieved some kind of cruising status. Am I correct on this? Can someone enlighten us about this event? We are concerned about having appropriate apparel if indeed we will be part of such an event. My husband doesn't want to bring a jacket as they are bulky and take up too much suitcase space. Any advice? Thank you in advance.

While it is possible to be invited to a Captain's dinner, it is highly unlikely, and you can always decline.