We went the Imagination 2 years ago and they used to have soda cards you could buy for your kids so they could have unlimited sodas from any where on the ship. Do they still have that or do you have to buy those individual coupons they are selling in the gift section?
Per Carnival's website, here's their current policy on the "Fountain Fun Card"...
What is the Fountain Fun Card?
We will offer to all guests the option to purchase a "Fountain Fun Card" which will allow them unlimited soft drinks for the duration of the cruise at a one time purchase price (including gratuities). The "Fountain Fun Card" can be purchased at any bar on board the ship. In all locations where beverage service is offered, guests may receive a glass of the soft drink of their choice - one glass will be served at a time and only to the guest whose name appears on the card. The card cannot be used through room service.
NOTE: A 15% gratuity will automatically be added on at the time of purchase of the Fountain Fun Card.
Cost for guests under 18 = $4 per day
Cost for guests over 18 = $5.50 per day
Free soft drinks in the dining room for children under the age of 12 is still in effect whether they have purchased a "Fountain Fun Card" or not.