Coffee is a naturally caffeinated beverage made from roasted, ground coffee beans and water. It is typically served hot.
Coffee in games, as in life, is sometimes used to provide a consumable boost to characters' energy or stamina. In The Sims, for example, characters can consume coffee to reduce their need for sleep, though consequently it also adds to the bladder meter, necessitating earlier or more frequent bathroom trips.
In Mario & Luigi: Superstar Saga the Marios Bros. can collect beans from across the world and blend them into special different coffees to increase their stats. In the tower defense game Plants vs. Zombies, coffee beans are a one-time use support unit that let the player "wake up" mushroom units usually reserved for nighttime levels so they can be used during daytime levels. The protagonist of Deadly Premonition, Francis York Morgan, has a particular fondness for coffee and manages to solve the murder case he is investigating in part by messages he apparently observes in the coffee.
The phrase "hot coffee" became an infamous euphemism for sex in Grand Theft Auto: San Andreas. While wooing women in the game world through dating mini-missions, amenable women would invite your character into their homes for "hot coffee". The phrase was also the name of a disabled sex mini-game in GTA: San Andreas, which hackers discovered and found ways to access, creating a firestorm of video game controversy.