First of all, there are no stupid questions. There are some that are harder to answer than others.
I am unable to answer your question, because I don't have a habit of sneaking.
We have been lucky enough that we can cruise, and buy a drink if we want one.
This is pretty much a moral issue. If you have no problem with cheating the cruise line, out of money, and if you have no problem with the rest of us having to deal with high prices, because not enough revenues collected on liquor, then I am sure you won't have a problem coming up with an idea on how to get booze on a cruise ship.
Please, for your sake and ours, don't drink so much that suddenly the ocean looks like you could walk on it.
We would hate that for your family, as well as all of us, who have already figured out that people do not fall off cruise ships.
Take care of yourself. I just lost my 20 year old son. Life is so short, and so less complicated when you follow the rules.
Enjoy your cruise.