Locks usually function just fine, but sometimes they burst open without any obvious immediate cause. In media of course this happens because the plot demands it, though it is occasionally deliberately used by a ConMan. This is typically at an inconvenient or embarrassing time (they grabbed a suitcase identical to theirs but filled with sex toys, which bursts open as they run 15 minutes late to a flight). Sometimes handwaved by having the container stuffed with something (say, money) that presses from inside, but that doesn't account for the timing.

Not related to PlotLock, which is about being forced to progress through the plot in a desired order. SisterTrope of PlotDrivenBreakdown; this can be reclosed immediately, though the contents may take some work.

* At the beginning of the first ''Anime/EdenOfTheEast'' movie, Saki's suitcase bursts open as the cabbie manhandles it, spilling guns and ammo and ''grenades'' onto the ground- not hers, but a setup by another character. How they got the suitcase to open at exactly the right time, though...
* In ''Film/MeetTheParents'', Creator/BenStiller's suitcase gets lost in-flight. A suitcase is found matching the description and delivered to him (at the parents of his girlfriend). He attempts to open it but can't and leaves for the day, leaving his prospective father-in-law alone at the house. Being former CIA he opens it easily and finds it full of fetish and bondage gear and sex toys.
* A standard trope of ConMan fiction.
* Sawyer of ''Series/{{Lost}}'' uses it repeatedly as a con man, to the point of lampshading when we encounter an alternate universe where he's a cop.
** Hurley falls victim when his suitcase springs open, causing him to miss his flight out of Australia. So he rebooks on the next flight, flight 815.
* At the end of ''Film/ItsAMadMadMadMadWorld'' the suit case carrying the money pops open, dumping the cash into a crowd of people.
* The ''WesternAnimation/SpongeBobSquarePants'' episode "Krabs Vs. Plankton". Mr. Krabs is sued by Plankton for slipping in the Krusty Krab, and his lawyer is indisposed, giving [=SpongeBob=] his briefcase, which he claims contains everything necessary to win the case. Unfortunately, the lawyer neglects to tell [=SpongeBob=] the combination to the lock, so he spends most of the trial struggling to open it. At the last possible moment, the briefcase opens, revealing [[spoiler:a Krabby Patty, which is used to lure Plankton out of his ruse and lose the trial.]]
* Near the beginning of ''Literature/TheSilverChair'', Eustace and Jill are escaping from some bullies towards a door that is always locked, and of course it turns to be unlocked. Justified in that Aslan has magically caused this to happen, but they don't know it at the time.