A character is doing something they would hate to be caught doing, whether it be illegal, out of character, or just plain strange. Naturally, that character would prefer to keep their actions hidden. So when an Innocent Bystander notices them, say, sneaking away from robbing a bank wearing nothing but a shower cap and an alligator purse, what's there to say to keep said bystander from blabbing the secret?
"Go ahead and tell everyone you know. No one will believe it."
This character has just created a Cassandra Bystander, taking Refuge in Audacity to create a Cassandra Truth, thereby ensuring their secret is kept safe and the bystander doesn't go blabbing. The circumstances around the creation of a Cassandra Bystander can be as lighthearted as a celebrity messing with a fan by doing odd things to as serious as some forms of Gaslighting. This may invoke You Wouldn't Believe Me If I Told You. If they go on to tell others, and are believed, it becomes a Tempting Fate.
Can be Played for Drama if, instead of a stranger, the bystander is someone who the character knows, or the secret that required the creation of a Cassandra Bystander is a crime committed to the bystander. Subtrope of Cassandra Truth. Compare and contrast to Cassandra Gambit, as a Cassandra Bystander is at most one or two people; more than that would mean the secret is out anyways. Compare Masquerade, which is about a conspiracy to hide something unusual from the public, and Shameful Source of Knowledge. Contrast Hidden in Plain Sight and Leave No Witnesses.
Examples
- The Adventures of Barry Ween, Boy Genius: When Mr. Goldblatt sees Barry and Jeremy chasing a dinosaur, they point out that he really doesn't want to tell anyone.
Barry: Say, Mr. Goldblatt, if you tell people that you saw a dinosaur being chased down Elm Street by two ten-year-olds in a Bronco, they'll think just two things...
Mr. Goldblatt: Alzheimer's and nursing home. [...] I didn't see nothin'.
- Feralnette AU: Chloe witnesses Marinette tearing an akumatizing butterfly apart with her bare hands. She coldly tells the shell-shocked Spoiled Brat that "Nobody will believe you".
- Strange Times Are Upon Us: Ila'kshath, a very large Gorn, surprises a deer hunter in 1859 Pennsylvania (Time Travel was involved). In response to his CO Brokosh pointing out the possible contamination of the timeline, Ila'kshath points out that even if the boy told anyone, they'd think he was telling tall tales.
- In this
Tracer x Widowmaker Overwatch fan comic strip, Sombra and Widowmaker discuss Tracer's loudness the night before, and Widowmaker says it was because she was eating Tracer's ass. She then goes on to say, bluntly, that she loves eating ass, thinks about eating ass morning, noon and night, and proudly proclaims herself "the best ass-eater". When a shaken Sombra asks why Widowmaker would tell her all this, Widowmaker smugly says, "Because no one would ever believe you."
- The Danny Phantom Recurring Fanon Character Wes Weston runs on this trope. Besides Sam and Tucker, Wes is the only other person in Amityville who's caught Danny transforming into Danny Phantom or vice versa. In most cases, Danny is fine with it—not only because no one would ever believe what Wes is saying, but because Wes looks a lot like him and anyone who'd see the physical similarities between Fenton and Phantom would always just assume Phantom was Wes instead.
- In Invasion of the Body Snatchers, Miles gets away from the pod people and begins trying to warn the populace, banging on cars in a maniacal way. One of the pod people says to let him go; it's not like anyone will believe him.
- An early Animorphs book has the team barely escaping being boiled alive as lobsters by demorphing. The poor woman, who just had to face three crustaceans suddenly growing and gaining human body parts, is reassured by Marco telling her it was all just a nightmare, and of course she shouldn't tell anyone about it, because then she'd get locked up.
- In Brooklyn Nine-Nine, Holt claims that he injured his wrist after tripping on an uneven sidewalk. He then privately reveals to Jake that he actually got hurt at a hula-hooping class, and shows Jake some photos.
Jake: (ecstatic grin) Why are you telling me this?
Holt: Because no one... will ever believe you. (deletes photos)
Jake: No! No...
Holt: (smug smirk)
Jake: You sick son of a bitch. - Community: Vice Dean Laybourne invokes this by putting an astronaut making paninis and a black guy dressed up as Hitler in the AC repair room; that way, those who escape the program and try to recount what they saw are laughed off.
- In an episode of The Greatest American Hero, Bill addresses a pair of crooks who experienced Ralph's superpowers when he captured them and tells them the last guy who blabbed about seeing a costumed man fly ended up in a straitjacket.
- In one episode of Lois & Clark, the villain learns Superman's identity through a time traveler's journal. At the end, Clark incinerates the journal and hands the villain over to the authorities, confident he won't be believed without evidence.
- The page quote from Mythbusters is spoken in one of the duct tape specials, positing how one would survive lost in a desert/river environment. By the time Adam says it, the two of them, decked out in tuxedos covered in dust from wandering around, are using a combination of bubble wrap, sticks, and duct tape to assemble rafts to go down the river. Not the weirdest thing they've done.
- In the The Twilight Zone (1959) episode "Long Live Walter Jameson," Walter Jameson is the fiancé of Sam Kittridge's daughter Susanna. After Kittridge learns that Jameson is more than two thousand years old, Sam tells Jameson that he will have to tell Susanna not to marry him. Jameson tells Sam to go ahead because Susanna will never believe him.
- Implied to be the mastermind's plan regarding Kokichi in Danganronpa V3. After Kokichi derails everything by pretending he is the mastermind and kidnapping Kaito, the real mastermind creates a flashback light convincing everyone else that he is a Remnant of Despair and they must stand against him as symbols of hope. The point of it being, since he's a liar, no one will believe Kokichi if he denies it and the mastermind's plans can proceed uninterrupted.
- One of the earliest strips of Ingrid the Plague Doctor has the main character invoke this on the reader, by revealing what she keeps under her black cloak, claiming that no one would believe them if they said so. The joke appeared again in the 25th episode of the rebooted series.
- Muted: The bird demon Raum is called back to the Severin family house, but can't teleport directly there because it's warded, so he lands outside... in a big dramatic cloak, his skin covered in feathers. He uses an illusion to change into an ordinary human in a Hawaiian T-shirt, and only then notices a lady standing next to him.
Raum: Whatever, it's not like anyone would believe you.
- In one The Simpsons Halloween special, Homer overhears Kang and Kodos plotting an invasion. They invoke this trope, but also spray him with rum to help seal the deal.
- The current page illustration of Bill Murray was more-or-less duplicated in real life with the publication of ''The Tao of Bill Murray'', a collection of Mr. Murray's exploits in what most of us consider off-screen reality.
