“You’ve got your friends on the Coast Guard to thank for that three ship’s worth of booze: the Nina, the Pinta, and the Canadian Club.”
You can unlock booze imports in Atlantic City. Speak to a business with a high enough relationship and they can give you a mission called Import/Export. For only $250 they’re opened up to importing booze from abroad for you in return for a Favor.
In return for taking this risk for you, you get the follow-up mission Bound Together in Common Interest. This will cost you $300 to $1000 (the amount seems to vary) but gives you an extra Favor to use for further imports.
 | Canadian Whiskey |  | Caribbean Rum |  | English Gin |
 | German Schnapps |  | Irish Whiskey |  | Scotch Whiskey |
Which type of booze they can import depends on their nationality and/or contacts, but they will only ever import one type of booze for you. Luckily, the people willing to import are dotted around the map so you’re unlikely to struggle finding all of them.
You get something like 10-15 bottles every time, delivered straight to a building of your choice.
The imported goods can’t be sold in any of the corner or small speaks, so you would have to go around and sell them manually, but there’s no shortage of buyers. Note: I haven’t unlocked Supper Clubs and higher in AC yet so don’t know if you can sell them there, but odds are you can’t.