Rum & Nuka is a variation of Nuka-Cola. This mixed drink, when consumed, will increase the player's Strength at a cost to their Intelligence and a small dose of radiation, plus one bottle cap is added to the player's inventory.
Because Rum & Nuka is an alcoholic beverage, the reduction in Intelligence is negated by having the Whiskey Rose perk. Unlike other forms of alcohol, Rum & Nuka does not carry any risk of alcohol addiction.
Can be purchased from the Garret Twins at the Atomic Wrangler Casino during a short period of time. In order for the Garrets to start selling Rum & Nuka, get to the point in Friend of the Followers where you tell James Garret that Julie Farkas agrees to the deal. Now ask James Garret "how's business?" He can reply in a few different ways. Keep asking the same question until he tells you he now sells Absinthe and Rum & Nuka. He and his sister should now be selling the drinks. At this point in the quest, James should have told you that he will be sending supplies over to Julie shortly. If you tell Julie about this, the quest will be completed and the Garrets, for some reason, will no longer stock either drink.
Unlike other alcoholic drinks, rum & Nuka doesn't have a flag set for food in the GECK, which means that it does not increase with the players Survival skill.