Simple Pleasures: Drinks

[NajdorfDefense]

Post in this thread mixed drinks with no more than 2 ingredients, plus ice or sugar.
An old favorite I have recently gone back to is the very simple:

Vodka and Bitter Lemon [Canada Dry]-
Pour 2oz Vodka [Chopin, Belverdere, Goose, whatever] into highball glass. Add bitter lemon soda [and ice cubes] to taste. No garnish.

What are some foolproof drinks you like with no more than 2 bottles needed to mix?