How it’s done in real life: You have to drink an amount of alcohol that goes beyond your tolerance level, then get behind the wheel of a vehicle. Legally speaking, it is a crime to drive in the US when your blood alcohol concentration is at or above 0.08%. Excessive drinking may be done by your lonesome or in a communal, party setting. Either way, those who drink and drive break state laws and ignore countless PSAs. They also put the lives of anyone who happens to be in the vehicle with them at risk. In most US states, convicted offenders of drunk driving laws spend time in prison, and are required to install ignition interlocks that prevent them from driving their vehicles if their BAC is deemed too high.
How it’s done in GTA: In GTA 4, Niko can complete the Drinking activity with his in-game friends and girlfriend(s). This shows a cutscene in which Niko and his friend walk into a bar, before cutting back to outside. When virtually intoxicated, you can still get into a car by pressing the Triangle / Y button. In this state, the screen becomes blurry, your DualShock or Xbox 360 controller rumbles, and the game becomes harder to control. Police will chase you if Niko is seen driving while intoxicated, until he loses his Wanted Level. If he is captured, he's released within a few seconds.