Stock Punishment

In which a character has their legs (or arms) restrained and has foodstuffs, preferably rotten fruit or veggies, cream pies, wet sponges or something else in that line of thought thrown at them by members of the public. Alternatively, stocks can also be used for Tickle Torture.

It is important to differentiate between stocks (which restrain the legs) and the more commonly used pillory (for the arms and head). Ultimately, however, the principal (it's commonly him in a High School setting) still gets the same humiliation -- all for a good cause.

A point seldom touched on in fiction is that being pilloried could be seriously dangerous. People were allowed to throw things at your head, and you could neither dodge nor block them. If you were lucky they would only throw fruit and vegetables (although you try getting hit in the face with a turnip and see how harmless that would be). If you were unlucky, they'd throw rocks. Or materials obtained from stable floors. And if you were really, really unlucky, it would be as bad as if you'd dropped the soap in a prison shower.

Rarely occurs with females (except when other stuff is done to them instead), for some reason.

Often used in Come to Gawk.

Examples:

Film

A Knights Tale has this happen to the main character while his friends try to defend him.
- Earlier in the film, there's a flashback to him as a young boy, watching the knights parade into the tournament grounds with his father. There's a man locked in the stocks right next to them, who advises young William that it would be easier for a man to change the stars themselves than for a peasant to grow up to be a knight.
Andersonville and it's not funny in that movie.

Literature

The Prince and The Pauper: The prince-as-a-pauper's friend, Miles, gets punished with these.
In the Aubrey-Maturin series, Captain Aubrey is pilloried after being set up for stock market fraud. The potential danger is made very clear but, in a Crowning Moment of Heartwarming, lots and lots of his old shipmates turn up to cheer for him and look menacing at anyone who so much as thinks about throwing things. Manly Tears may have been involved.

Live-Action TV

In an episode of Sabrina the Teenage Witch, there is a fieldtrip to a Salem Witch Trial themed village. At the end of the episode the Alpha Bitch Libby ends up in the stock, but does not get things thrown at her.
Black Adder The Third: Edmund invites Prince George to star in his new play, "Thick Jack Clot Sits in the Stocks and Gets Pelted with Rancid Tomatoes. George naturally agrees enthusiastically.
Merlin- a bit of a Running Gag for the titular character- happens in the first episode when he picks a fight with Arthur, three times in one episode. The Children in Need scene naturally features it.
In an entirely serious example from the George III-era Very Loosely Based On a True Story Costume Drama Garrows Law (coming soon to a US TV station near you...), William Garrow exposes Forrester, a professional "thief-taker" - basically a man who is paid to fit people up - as a perjurer. The judge sentences him to two hours in the stocks - a pillory in this case. He gets the rotten fruit treatment, then we see the grandmother of the boy he murdered as part of one such scheme pay the man who turned on him. The man then throws a rock...
- A similar thing happened to Mother Needham, the notorious bawd, in Channel Four's drama-documentary of Hogarth's A Harlot's Progress.
- Kind of Truth in Television. Unpopular people put in the stocks faced a real risk of being beaten to death by angry mobs. Some people even wore armor when in the stocks in order to avoid this.

Video Games

The title heroines of Beat Blades Haruka, Ikusa Otome Valkyrie, and Himekishi Lilia all get scenes in which they are locked in pillories and raped.
In The Sims Medieval sims can end up in the stocks from failing to complete responsibilities, stealing, or just because the player felt like it.
Lego Pirates of the Caribbean uses this to replace scenes where people were hanged in the movie.

Web Comics

Bruno The Bandit often ended up in one of these - mostly when the judge had run out of Cool and Unusual Punishment for him.
In Sinfest, there's a pillory, as yet unoccupied, in the dungeon that Squidly falls to.

Western Animation

There's one guy in Disney's The Hunchback of Notre Dame who is stuck in these. Used as a joke: he always gets out of things like stocks exclaiming "I'm Free! I'm Free!" and falls into another trap (an open manhole, etc.), muttering "Dangit!"
Disney's Beauty and The Beast also has a guy in these tipping his hat to Belle at the start of her I Want Song.
Looney Tunes: There are several.
The Simpsons did an odd version of this where they were deemed bad parents they were forced to wear portable Stocks 24/7 and then had additional punishments added onto such as standing next to a road while motorists spanked them as they drove by.

Wiggum: Hey, no extension cords!

Used in the Trollz story arc where the town was sent back to the Middle Ages. The girls were put in pillories. Among other things, croutons were thrown at them.
Used in Ka Blam! when Henry and June were visiting Colonial Williamsburg, and ended upin stocks at the end (I guess they were too nineties)