We love to experiment with homemade bitters and infused syrups, but sometimes you just want a cocktail that's simple and fuss-free. Luckily, there are tons to choose from. In fact, many of the most classic cocktails have just a few ingredients. For those days when you want a drink fast, or when you want to serve a crowd without slaving away behind the bar for hours, here are 18 yummy beverages that require only two ingredients. Cheers.