In this scene from the 1967 anti-scare film, Narcotics, Pit of Despair, a callow college student enters a dope den filled with spaced-out hippies who cajole, harangue, guilt-trip, and bug him until he succumbs to their mind games and shyly takes his first puff of a marijuana cigarette.
His wild night affects his studies the following day. He realizes the serious consequences of his slip-up after receiving a D on his test.
Sadly, the young fellow doesn't learn his lesson, and his trip on the hedonic treadmill leads him to heroin, the fate of everyone who tries smoking pot.
[via r/WeirdLikeMe]