Help! Help! I'm Trapped in an X Factory!

Someone is trapped, or forced to work against his will, in some kind of facility that produces publicly available goods (such as fortune cookie fortunes, or candybar wrappings). He proceeds to use them as a means of communicating with the outside world and asking for help.

In comedic versions, it's usually just a throwaway gag, and the fate of the mysterious victim isn't ever alluded to.

By the way, I'm trapped here, and they are forcing me to type up trope entries! Send help!

Examples:

The earliest use that has been found for "I'm being held prisoner at [a Chinese food preparation place] is from 1955 (listed here) but some suspect that it's been around for longer than that.

Literature

A message in Hogfather is in a Christmas Cracker and says "Help help help Ive fallen in the crakker machine I cant keep runin on this roller please get me ou-". Someone says it's the same old mottos as when they were kids.
In Goldfinger (the original novel) James Bond leaves a note on the underside of the toilet on a plane, telling of Goldfinger's plot and saying that delivery of the note to Felix Leiter of the CIA will result in a reward, hoping that the cleaning crew will find it; but doesn't know whether or not it got found & delivered, or thrown out, or found by the bad guys.
In The Tightrope Walker by Dorothy Gilman, the plot starts when the owner of a second-hand store finds a "Please help" message hidden in one of the objects in her store.

Live Action TV

The "...Chinese Fortune Cookie Factory" version was used on Get Smart.
News Radio, Dave is reading cards from a complaint box.

Dave: "Help, I'm being held prisoner in a complaint box", which is actually kinda funny.

One Mock the Week Scenes We'd Like to See round gave us Unlikely Things to see on a Round Sign to which Frankie Boyle provided us with...

Frankie: Help I'm trapped in a sign making factory.

Newspaper Comics

Comes up in Peanuts during a Story Arc where Linus's mom leaves him inspirational notes in his Brown Bag Lunch: one reads "Help! I'm being held prisoner in a School Lunch factory!"

Tabletop Games

The flavor text on the humorous Magic the Gathering "Gleemax" card.

Video Games

Fairy Godmother Tycoon has a story part where someone finds a wig -- there's a little note attached. "Please help. Kidnapped. Forced to make wigs. Rapunzel."

Web Comics

The eye chart in the first panel of this Gunnerkrigg Court guest comic.
Has been parodied twice in Xkcd. First there was the Pi Equals comic, and the second was in the Alt Text of Exploits of a Mom.
- xkcd fans like variations of this too.

Western Animation

Looney Tunes: The Daffy Duck short "China Jones" parodies the "being held in a Chinese bakery" one. Daffy himself ends up being held in a Chinese laundry.
The episode titles the first part of Robot Chicken's fourth season form the message "Help me. I'm trapped in a DVD factory. They took my thumbs. Two weeks without food. Tell my mom I love her, but not in that way. Love, Maurice PS: Yes, in that way." In a twist to this trope, the second half's episodes titles make up the factory's response: "Dear Consumer, we are a humble factory. Maurice was caught unionizing our labor. President Hu forbids it! Due to constraints of time and budget, the ramblings of Maurice cannot be erased, so sorry. Please do not notify our contractors. Especially the animal Keith Crofford!"
There was a Madeline animated movie where Madeline ended up in a sweatshop making lace, and she and the other girls attempted to knot lace patterns that spelled out a message for help.