Robert Evans gives a Real Life example in his autobiography The Kid Stays in the Picture in which he was offered pharmaceutical grade cocaine during the early 1980's, which he described was "mythical" at the time. He evenlabelsit schmuck bait, and castigates himself, "How could I be so fucking stupid?!"
Robert Evans: A woman we knew was offering to sell us pharmaceutical cocaine at bargain prices. Pharmaceutical cocaine was mythical manufactured by only one company in America, Merck. So mythical was its allure, that it became the DEA's most effective bait to entrap schmuck buyers.
Occurs in the backstory, too. Uncle Andrew tells Digory the story of how his godmother gave him a box before she died making him promise to destroy it without opening it after she died. Opening it started him on his quest to be a magician, which eventually was the cause of Digory and Polly traveling to other worlds in the first place.
Used or referenced excessively in Terry Pratchett's Discworld series. Anything in Discworld that is labeled "Do Not Touch" will be meddled with.
In the very first book, Rincewind gets stuck with the Eighth Spell of Creation because he went and opened the Octavo on a dare, when every student was perfectly aware that it was not to be touched.
The wizards of the Unseen University are the people who put the Schmuck in Schmuck Bait. As a footnote explains: Any true wizard, faced with a sign like "Do not open this door. Really. We mean it. We're not kidding. Opening this door will mean the end of the universe," would automatically open the door in order to see what all the fuss was about.
In Hogfather, Archchancellor Ridcully discovers a hidden door, which his predecessor had had sealed off, leaving a sign saying, "Do not, under any circumstances, open this door." So, naturally, Ridcully has it unsealed. One of his subordinates asks if he'd seen the sign, and Ridcully says, "Of course I've read it. Why d'yer think I want it opened?" When it's sealed again at the end, the Genre Savvy worker makes sure to leave the nails loose.
A footnote says, 'this exchange contains almost all you need to know about human civilization. At least, those bits of it that are now under the sea, fenced off or still smoking.'
Perhaps not coincidentally, in the novel Thief of Time, Lu-Tze reasons that he should go to Ankh-Morpork, a veritable city of schmucks, because "the day someone pulls the plug out of the bottom of the universe, the chain will lead all the way to Ankh-Morpork and some bugger saying 'I just wanted to see what would happen.'" Guess what city the Unseen University is in?
Also in Thief of Time, a narrated line points out, "If you put a large switch in some cave somewhere, with a sign on it saying 'End-of-the-World Switch. PLEASE DO NOT TOUCH,' the paint wouldn't even have time to dry."
Again in the Thief of Time where the concept is inverted, played-with, subverted, taken out behind the Mended Drum, kneed in the groin and thrown in the River Anhk: The heroes set up a series of possible schmuck baits to confuse the literal-minded auditors—"Do not feed the elephant" when there is no elephant to not feed, for example.
In The Last Continent, the wizards discover a window that has been turned into a portal to a desert island. The Archchancellor props it open and attaches a warning that 'showed some thought has gone into the wording: "Do not remove this wood. Not even to see what it does. IMPORTANT!"' It half-works, as somebody later removes it... accidentally.
In Soul Music, the Librarian picks up on the beat that is infecting the world, and pulls out all the stops on the University's mighty organ, including the ones "with faded labels warning in several languages that they were on no account to be touched, ever, in any circumstances" before he begins to play. This is mostly to illustrate the magnitude of the music, since nothing extraordinarily bad actually happens when he plays. There's the wall of noise and the explosion afterwards, but that's par for the course when it comes to musical instruments designed by Bloody Stupid Johnson. Considering it was a Johnson, they were lucky it didn't blow up when you stepped on the pedals.
The reason for the labels may have been provided in Hogfather, in which the existence of the "Organ Interlock" mechanism in the sealed Archchancellor's Bathroom is demonstrated, to Ridcully's great distress.
The circle of stones up on the moor in Lancre, mentioned in Lords and Ladies. They're there partly to keep the elves out, and partly "in the hope that enough daft buggers would take it as a warning, and stay away." Guess what happens. Subverted in that the circles are described as safe and stable (except for the very rare times when the universe barriers are weak) and thus the villagers of Lancre specifically don't forbid the children to hang around the circles, simply because they know that this way, the kids will quickly lose interest.
Also in Lords and Ladies, when Magrat surrenders to the Elves, she hands one a box telling him not to open it. He does, and answers the Discworld version of Schrodinger's cat (the states of the cat can be dead, alive, or alive and bloody furious) as "Greebo went off like a Claymore mine".
In The Last Hero, it's revealed that mysterious treasure maps, and accompanying tales of how perilous the treasures' locations are, were placed in the paths of gullible heroes by the gods, who consider Schmuck Baiting a spectator sport.
In Carpe Jugulum the vampire Count de Magpyre and his ancestral home, Dontgonearthe Castle. People came from all over the country to see what the fuss was about, eventually necessitating the installation of road signs along the lines of "Last chance not to go near the castle, 100 metres on your left" and directions on how not to go near the carriage park. At the end of the book the count is having a gift shop installed. This is something of a Lampshading/Subversion as it's part of an unspoken agreement between Vampires and Humans: As long as heroes continue to be schmucks (and vice-versa), Vampires will continue to stock their castles with convenient crosses, bundles of garlic, easily-pulled-aside curtains and breakable wooden furniture — as opposed to enslaving humanity, while villagers will continue to pretend to believe that the old vampire that they killed a century ago couldn't possibly have returned, for at least another century or so, before killing him for another century or so.
Going Postal has Vetinari offer a nice cushy job to two former criminals as an alternative to execution. He tells them that if they like they can simply walk out the door and never hear from him again. Both men are smart enough to guess that a quick death lurks beyond that door, and make informed decisions.
Also subverted in Making Money, where Moist expects the missing floor and is surprised when it is now a normal room.
In Making Money, Aimsbury the chef is allergic to the word garlic. Not actual garlic, but the word; if someone says "garlic" near him, he briefly goes catatonic before throwing anything he might be holding and shouting in fluentQuirmian for eight seconds straight. People often find themselves with an inexplicable urge to say it, which can actually be dangerous for anyone standing directly in front of him while he's holding a kinfe.
In The Hitchhiker's Guide to the Galaxy, Arthur Dent spots a big red button next to a sign that temptingly reads, "Please Do Not Press This Button". He presses the button only to have a warning message appear that says, "Please Do Not Press This Button Again".
There's a failed attempt at Schmuck Bait in The Hounds of the Morrigan by Pat O'Shea. Some mooks charged with capturing the protagonist set up some road signs: "This road is the winner of the Safest Road in Ireland competition. This road is so safe that a boy can cycle down it with his eyes shut." The boy keeps his eyes open and easily avoids the feeble roadblock set up to trip him. Obviously the mooks didn't grasp the fundamental principle of Schmuck Bait — they should have told him not to shut his eyes.
Alastair Reynolds' Revelation Space series is loaded with schmuck bait, most of it left behind by the Inhibitors. There are unusual alien artifacts designed to get attention of intelligent space-faring life forms and contain difficult puzzles as locks. If you're smart enough to open it, it signals the Inhibitors to wake up and come exterminate your race for being too intelligent. The artifact found around the neutron star in the book Revelation Space is transformed into Schmuck Bait by a later culture, the Amarantin's (genuine) attempts to disguise it, keep others away and warn them.
The Gunslinger: Whatever you do, Allie, don't tell Norm "nineteen". Given that it's a Stephen King book, it's played for suspense and terror. Norm, incidentally, is a man who was bought back to life, and after Allie tells him "nineteen", whatever he tells her is so horrifying she begs the lead to put a bullet between her eyes.
One book in the Enchanted Forest Chronicles mentions a well full of Water of Healing, which has hanging nearby two dippers: an ordinary one, and a golden, jewel-encrusted one that turns to stone anyone who touches it. One of the characters in the book is a prince who was Genre Savvy enough to know not to use the gold dipper, but still picked it up to take a look at it (after all, it's not every day you see a golden, jewel-encrusted dipper); when he started turning to stone, he thought quickly and dipped his arm into the water, making him a living statue.
In hinting at what the whole revealed, I can only hope that my account will not arouse a curiosity greater than sane caution on the part of those who believe me at all. It would be tragic if any were to be allured to that realm of death and horror by the very warning meant to discourage them.
In an earlier story, The Case of Charles Dexter Ward, the Big Bad Joseph Curwen receives a letter from an associate giving him this little gem of advice: "I say to you againe, doe not call up Any that you can not put downe; by the Which I meane, Any that can in Turne call up Somewhat against you, whereby your Powerfullest Devices may not be of use. Ask of the Lesser, lest the Greater shal not wish to Answer, and shal commande more than you.". Guess what he tries to do later on.
A town able to inspire such dislike in it its neighbors, I thought, must be at least rather unusual, and worthy of a tourist's attention.
Briar Patching (as introduced by Joel Chandler Harris's Uncle Remus stories) is a particularly active form of Schmuck Bait.
Arguable, but the Imperial Infantryman's Uplifting Primer has a page in it that has a large blanks space labeled, "Do not deface. ON PAIN OF DEATH!" Nearly every owner of the Primer has scribbled something in that space.
In Robert W. Chambers' short story collection The King in Yellow, almost anyone who reads the eponymous fictional play has had to intentionally seek it out and is therefore well aware of the fact that anyone who had already read it was quickly driven insane. So why do they still read it?
The opening of Houseof Leaves specifically tells the reader not to read the book.
In The Belgariad, the nomadic Algars have one massive self-sustaining fortress for the sole purpose of acting as bait for invading armies. Being nomads, they never actually are there, but over the centuries nobody's caught on. They do visit the place, they just don't stay there long. They temporarily (did we mention nomadic?) set up housekeeping around it while Gareth and company are visiting, mainly for the purpose of, essentially, doing minor repairs and light weeding so that it doesn't start to look too abandoned.
How bad does this get? During Torak's invasion of the west, he and the Angaraks laid siege upon it for ten years, and only stopped because the prophecy that led him on told him he had to be somewhere else at a certain time. Otherwise, he would probably be there until every Angarak he brought with him was killed or starved to death.
Harry Potter: The Headmaster of Hogwarts would like to remind you that the corridor on the third floor is off-limits to absolutely everyone. As well as the Forbidden Forest.
The groundkeeper Rubeus Hagrid would like to add that the huge three-headed dog behind the easily unlockable door in said corridor doesn't guard anything of any interest to students.
Deputy Headmaster Minerva McGonagall would like to affix that the legendary Chamber of Secrets allegedly built by Salazar Slytherin and containing some unspeakable horror, most certainly does not exist, and thus students should not divert their attention from their studies to the knowingly fruitless searches of said Chamber.
Death would like to offer you the Elder Wand, a wand so powerful it will make any wizard who wields it unbeatable. Just ask the hundreds of dead wizards who owned it before you.
Arabian Nights contain the story of The Man who Never Laughed During the Rest of His Days. A young man is charged with taking care of his rich but gloomy uncle and his friends, who spends all their time grieving over some terrible fate that has befallen them. The uncle tells his nephew that he will inherit all his riches as long as he never asks the grieving men about the reason behind their sorrow. On his uncle's deathbed, the young man's curiosity makes him break his promise and ask anyway. The uncle then tells him that if he wants to avoid a terrible fate, he mustn't ever open one of the doors in the building. After the uncle dies, the young man inherits the house and is happy until his curiosity gets the better of him. He opens the forbidden door and finds himself in an earthly paradise ruled by beautiful women where he is immediately married away with the queen, who lets him rule by her side. But she also tells him that he must never open one of the palace doors. The young man spends seven happy years with his queen, but eventually cannot stop himself looking behind the forbidden door. He finds himself back in his home and unable to return to the queen and the paradise kingdom. He thus, just like his uncle and the other grievers, end up as the titular man who never laughed during the rest of his days.
The miners in SporeDug Too Deep in an asteroid and found a Door of Doom with recorded warnings (now destroyed) and, in case those failed, a terrified-looking statue outside. Best guess anyone, including a visiting anthropologist, has is that it's some kind of tomb. The miners decide to open it anyway in case there's treasure. There's not.
There is a failed bit of Schmuck Bait in The Road by Cormac McCarthy. The man finds a jar of preserved fruit in an abandoned house. It looks very nice, but "other people hadn't trusted it, and in the end, neither did he."
In To Sail A Darkling Sea by John Ringo, the non-infected humans place modified cargo-carriers where zombies can approach it. The cargo-carriers have sirens and lights to draw infected 'zombies' in. Schmucks go in, chum comes out.