I don't want to know either. I have a friend that will get the necessary items together for us to find out together on the trip.
If your can make a cake with that color in it but may be difficult on an cruise.... But honestly I think having him there would be best. Or if he can't have tech write it down on a paper and find out on cruise together.... Or last thought buy am outfit of either color pink or blue and have him open a present and find out that way