A buck is a cocktail that is made with ginger ale or ginger beer, citrus juice, and any of a number of base liquors.

[1] Buck cocktails are sometimes called "mules" due to the popularity of a vodka buck that is known as a Moscow mule.

The buck is believed to have gotten its name when someone added a shot of whiskey to the previously nonalcoholic Horse's Neck, which consisted of ginger ale with lemon juice.

The added alcohol gave the horse a "kick" – hence, a bucking horse.

[2] Variations include: