A group has found an item (an artifact, some piece of supposedly incomprehensible technology, etc.). The group, most likely including the smart guy, starts discussing how it will take quite a bit of time and research to discover the item's purpose and/or how to use it. Meanwhile, another person in the group (often The Hero, but not necessarily) is fiddling around with the item, and unlocks/activates/arms/whatevers the device, interrupting and possibly upsetting the others in the group.
In cases where the method of using the item in question is discovered by someone of lesser intelligence, this trope becomes a specific example of Too Dumb to Fool.
Compare Luck-Based Search Technique, where the person or group is actively trying to solve whatever puzzle is present, inadvertently finding a solution through dumb luck. The main difference between these tropes is a matter of intent; the luck-based searches begin intentionally, while a chance activation is just someone fiddling with a Plot Device and it "working".
- Wonder Woman (1942): Etta and Steve Trevor are discussing how impossible it's going to be to get a spacecraft they're in to do anything and Etta manages to launch them both into space by plugging in two wires and pulling a lever. Neither are pleased since it was accidental, the government is probably going to charge them with theft and they still have no clue how to actually control it.
- Occurs in Treasure Planet, after the Benbow Inn has been burnt down and the Hawkinses are staying with Dr. Doppler. The good doctor is explaining that he has no clue of function of the "odd little sphere" which Jim now possesses. Cue Jim fiddling around with the sphere and unlocking it, thereby discovering its function; a map containing the location of the legendary Treasure Planet.
- In The Batman vs. Dracula, The Penguin just happens to cut his hand on his umbrella-sword, giving Dracula the drop of blood he needs to rise from the grave.
- In Aladdin and the King of Thieves, Razoul the guard tries to break into the stronghold of the Forty Thieves, but he can't remember the password. After repeated failures ("Open — carraway!"), he leaves in disgust, only for one of his guards to offhandedly comment, "I thought he said it was 'Open Sesame'?"
- The Air element stone in The Fifth Element is opened by pure dumb luck (David sighing at it in frustration), providing the key clue needed to open the three others: they have to use the Four Elements to open the stones — air, earth, water, and fire.
- The gun over the bar at the Winchester in Shaun of the Dead. Slightly different, in that they knew how to use it, they just thought it wouldn't work. And then it goes off in Shaun's hands.
Ed: I fucking knew it!
- In the Green Lantern movie, Hal has been given a magic ring and a magic lantern by the dying Abin Sur, but no instructions on how to use either, nor what the Green Lantern oath is supposed to be. He fools around with both for the better part of an afternoon, offering a number of possible activation phrases (including "By the power of Greyskull!" and "To infinity and beyond!") until he gets the connection just so and the ring and lantern take over for him.
- Seen in The Cabin in the Woods, and exaggerated: the five teenagers go into the cellar, and each one starts fiddling with a different mysterious object (necklace, music box, puzzle sphere) — and only when one girl reads aloud from a book does she "Activate" it. On the other side of the screen, the organizers of the scenario resolve their betting pool on which monster was going to be summoned.
- In Five Children and It by E. Nesbit, while everyone tries to figure out how to open the door, the baby is playing with the lock. The door swings open.
- In The Cloakmaster Cycle Teldin was not amused to know some possible results of Tinker Gnomes' "thingfinder" malfunctions and when it got damaged he ordered another guy to quietly get rid of it. Thus the trinket ended up in a jettison (sort of catapult used as Short-Range Shotgun) and eventually was fired at an enemy. On impact, Hilarity Ensues.
- In the Discworld book Thud!, It's revealed that this is how Mad Artist Methodia Rascal activated (and was subsequently driven even crazier by) the dwarfs' talking Cube. As he thought he was a chicken, the noises he would make (Awk! Awk!) happened to sound like the Dwarfish word that turned it on.
- In Deltora Quest Lief doesn't realise that the Belt of Deltora has to be activated at all - and then realises that the stones need to be in a very specific order. The Belt had been working at minimal strength until he figures that out.
- Ciaphas Cain: In keeping with their usual track record of messing with Necron artifacts (several balls in a large slotted slab, producing different effects depending on number and position of balls), the Adeptus Mechanicus manages to summon a daemon, which Cain is fortunately able to take out rapidly..
- In the first episode of Black Books, Fran mistakenly buys a large spherical object with a teapot-like spout to sell in her curio shop. She spends most of the episode obsessed with discerning the object's purpose. In the final seconds of the show Bernard pats his pockets, looking for a light for his cigarette. Without thinking, Manny picks up the strange object and squeezes it, producing a flame from the spout which he lights Bernard's cigarette with. Fran lets out an exasperated scream.
- At the end of the very first mission of Mass Effect, Shepard's squadmate (Ashley if Shepard is male, Kaidan if Shepard is female) activates the beacon they've been looking for by simply walking too close to it.