The popular "Rum Runners" used to smuggle booze on board basically looks like a colostomy bag with a cap on it.
People have been smuggling booze ever since the cruise lines stopped allowing passengers to bring it on.
A few years ago we spent a couple of days pre-cruise in our embarkation port (I actually can't remember which one) and my wife bought a pint of vodka for evening cocktails. When it came time to go to the ship she still had half of it left. Being the "frugal" woman she is there was no way she was going to get rid of it and she put it in a Sprite bottle and put it in her luggage. It made it through with no problem. The only problem was that I had no idea of what she had done. I was sitting at the desk and the bottle of Sprite was right there so I opened it and took a drink. Let's just say I was "surprised".