Potion of booze
A non-blessed potion of booze will make you confused for 3d8 turns. ("Ooph! This tastes like liquid fire!") It will also provide some nutrition and abuse your wisdom. (10 nutrition if cursed, 20 if uncursed, 30 if blessed, regardless of dilution.) If the potion is cursed, it will make you pass out for up to 15 turns. If the potion is not diluted, it will also heal 1hp. A blessed potion of booze will not cause confusion.
Potions of booze are sometimes used in conjunction with the Scroll of gold detection on the Elemental planes to detect magical portals, or in conjunction with the scroll of enchant armor to prepare for the fire traps in Gehennom, especially by Monks and Wizards, but note that this is only useful with uncursed potions, since the desired effect is confusion.
Dipping an amethyst into a potion of booze will turn the potion into a potion of fruit juice. (This is a reference to amethysts' name coming from the Greek for "not" "drunk". See the article on amethysts for more detail.)
junk >> water >> sickness >> fruit juice >> booze >> blessed booze.
Foodless runs supplemented by potions of booze are not recommended in real life. In medieval Europe, the craft of beer brewing was greatly advanced by monks who had to survive long fasting periods.