In this classic clip from The Simpsons, Mr. Burns and Smithers navigate an absurdly complex security system inside the Springfield Nuclear Power Plant. Set to a jaunty 1960s-style spy theme complete with heavy brass and woodwinds, they pass through a series of hand-scanners, iris doors, and even firefighter poles labeled with their names in a fun nod to the classic Batman series. Eventually, they arrive in a library and pull a secret book on a shelf around 0:21 to swing open the hidden wall.
The punchline hits instantly when the secret passageway opens up to reveal a standard exterior door left wide open, complete with a stray dog wandering into the compound. Burns throws his hands up at 0:24 and mutters, "Oh, for God's sake!" It's a fantastic piece of classic Simpsons visual humor that perfectly parodies supervillain lair tropes only to immediately subvert them with mundane incompetence.