Here is a link to the Carnival site.
Most times when you book they will ask if any special occasions..get on the ball with your travel agent!
I must make a disclaimer before the following statement that I am in no way soliciting business and is a hypothetic scenario if I was a Cruise agent.
But if I was and you were my client, you would at least get the cake or a bottle of Asti on your special night with my compliments.
Now get busy and make this happen
Best to you, IslandCruz