Carnival has the Fun Fountain card. No sticker anymore.
Another thing to consider with the card is that its only good for fountain drinks in GLASSES. You don't get a lot of soda in a glass. For $2.0 you can get a bottle of soda from the bar which is probably 3 glasses worth. Besides, the hassle of having to get a bar tender to get another drink is a headache. We get a card for the kids because they drink more soda and its cheaper for them. But for me, the one time I got one, I felt I wasted money. I drink real drinks in the evening and wine with dinner so I didn't get enough soda to make it worth the money. But if you drink a lot of soda and only soda, its not a bad deal. The earliey comment about needing to drink 3 sodas a day is about what I figured out also.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013