When it comes to the best drug movie starring Al Pacino - who turns 76 today - the image of mobster Tony Montana ploughing through a mound of cocaine on his desk in "Scarface" (1983) is the first thing that comes to mind. But Pacino also fought on the right side of the law in "Serpico" (1973), which includes an amusing scene where the title character and other undercover cops are given joints to help them get into character.

"I am passing out these marijuana cigarettes for you to sample," their superior says while a tray of joints circulates around the room. "So that when you become plain-clothes-men, you'll be able to identify the pungent aroma and recognize the disorienting effect of the drug when you observe them in narcotics suspects."

The police gladly partake in the immersive crash course by lighting up in the room at the station. "Hey, this is real good shit," Serpico's deskmate says. Given Pacino's reputation as an intense method actor, you have to wonder if that joint was real - especially considering the rumors that he began casually smoking marijuana in his teens.

The scene from "Serpico" also demonstrates how quickly marijuana can lead to violence and depravity as one of the cops gets the munchies and tries to mug a vending machine. Check out the full clip below: