Monkey Wrench

A Monkey Wrench is a simple, refreshing cocktail made with dark rum and grapefruit juice, typically served over ice in a highball glass. The bittersweet tanginess of grapefruit juice pairs naturally with the molasses-forward depth of dark rum. Some variations add a splash of grenadine or simple syrup to soften the grapefruit's bitterness.

The name Monkey Wrench is believed to derive from mid-20th century American slang, evoking the idea of a drink that 'throws a wrench' into one's sobriety — a playful nod to its deceptively smooth but potent character. Some sources associate it with blue-collar cocktail culture of the post-war era, when simple spirit-and-juice combinations were popular. The name has no confirmed singular origin story.

A Monkey Wrench typically has an ABV of around 12–16%, with dark rum at 40% diluted by a large portion of grapefruit juice. Recipes generally call for 1.5–2 oz of rum topped with 4 oz of fresh or bottled grapefruit juice. The low apparent sweetness and high carbonation in some variants make the drink feel lighter and more refreshing than its alcohol content suggests.