Whats the best way to get alc on a cruise ship?

Security is similar to that in an airport and your luggage is x-rayed so there is no way you could smuggle on board an obvious booze bottle. You might get away with decanting some into toiletry bottles and putting these in your toilet kit, labelling them "after shave", etc.

Rum runner flasks are deffinatly the bast way to get alcohol on board. I've been on 5 cruises and we use these every year. There clear, and plastic so they don't show up on the xray. And they rarely check your bags, but just in case, we wrap them in our towls. :) http://www.rumrunnerflasks.com/

Put it in a water bottle or gatorade and put in checked baggage.

Let's see -- you are under the legal drinking age, concerned about your parents finding liquor, and are asking advice about smuggling it on board. You say you can't risk putting it in your regular suitcase, which leaves your carry-on, which allows only those liquids in 3 ounce amounts, all of which have to fit into one 1-quart baggie. Also, you apparently aren't worried about being denied boarding (with no refund and no recourse) or later being tossed off the ship bag and baggage with no apology, no recourse, and no refund but with the need to find and pay for your own way home. Notwithstanding all of that, you are planning to take all those risks. Is drinking on board a ship really that important to you? When you are on shore in the ports where you do meet the legal drinking age you can drink yourself silly if you like. As to the rest, you might want to consider re-evaluating your priorities.

If you are flying, you can't put liquids in your carry on, except for 1.5 oz containers ZipLoc'ed. I would disguise it. Perhaps you could fill a couple Dasani bottles with vodka, or if it's whiskey, use a Listerine bottle. I would ZipLoc them anyway in case of leakage.

You can always put it in "natures pocket" like the prisoners I bust do.

You can't have any liquids over 3 oz. in a carry on. You best best is to find the nearest bar when you get to each port. Just make sure you get back to the ship on time or it will leave without you. (although I have actually seem them take wheelchairs to the bar to bring back the college guys that were too drunk to walk) Be careful though as it's when you've had too much to drink that somebody picks your pocket.

go to the cruise ship's kitchen and you might find one, but don't let them see you or caught you.