Mills and Boon Prose

Overcome with his intense passion, Drake manfully thrust hard with his throbbing equipment, again and again, oblivious to the inevitable consequences of his actions and reveling in the sensual pleasure of using his electric toothbrush in a simple to and fro motion rather than brushing in small circles as his dentist had advised, and hoping that Cecelia would appreciate his minty fresh breath over dinner later that evening more than the damage he was doing to his enamel.

—Irregular Podcast! #13, "The Complete Works of Western Literature"

The traditional way of handling sex in a Romance Novel; Purple Prose to IKEA Erotica's Beige Prose. Physical actions and sensations are conveyed via vague euphemisms or even overblown (heh heh) metaphors—while emotions are described in excessive, abstract detail. Often one suspects that the writer wishes he or she were participating in the scene. A sure sign that you've got one of these is when abstract nouns are used to refer to genitalia.

Popularly associated with, but not limited to, sex scenes. Any interaction between the main characters is fair game for this sort of emotionally charged description.

This is becoming rare in real romances, which are beginning to eschew floweriness for harder-edged (and sometimes downright vulgar) prose. However, Mills and Boon Prose lives on in parodies, often used to invoke Innocent Innuendo. It also occurs in Fictional Documents as a form of Stylistic Suck. Can involve Anatomically-Impossible Sex.

No real life examples, please; this is All The Tropes, not Tropes After Dark.

Examples of Mills and Boon Prose include:

Advertising

Spoofed in a 2008 ad for McCain oven chips in the UK, where a woman eating the chip is described in this way.

Anime and Manga

R-15: The protagonist is a porn writer. He does this often, in a light novel that does this just as often.
Erika Karisawa from Durarara!! doesn't just think like a slash fanfic - she thinks like one written entirely in Purple Prose.

Fan Works

Stray uses a variation of this. There are no throbbing manhoods or heaving bosoms, but the first sex scene includes at least two separate extended metaphors for the POV character's emotional state.

"From the towers where they hid in the most heavily fortified territory of Adamska's heart, overlooking the waterfall that fed into its own source, the last loyalists to the old aristocracy said to hell with it, threw down the torches, unbarred the doors, and ran outside to join the party."

- Spacedust and Chaos: A Requiem. There's shagging going on but it's kind of hard to tell.
Parodied in the The Real Ghostbusters story Sweet Temptation. It turns out to be Slimer watching a cooking show.

Film

Also parodied in The Naked Gun 2½:

"His strong manly hands probed every crevice of her silken femininity, their undulating bodies writhing in sensual rhythm, as he thrust his purple-headed warrior into her quivering mound of love pudding."

The principal from 10 Things I Hate About You tries writing one of these when not busy in her office. Hopefully the only time the word "bratwurst" is used in an erotic novel ever.

Literature

Stereotypically associated with Mills and Boon (UK) and Harlequin (US) novels.
Twilight. The acts themselves were done with a fade to black, but the characters discussing how vampire sex feels... oh boy...
Parodied in Dave Barry's Guide to Marriage and/or Sex:

"As Sabrina gazed upward at Baron LeGume, whose dark, brooding eyeballs were turgid with passion, she felt the tormented tenseness of his throbbing, pulsating malehood, and she knew, with a knowledge borne of knowing, that she could no longer hold back the surging waves of passion that washed over her, like waves of something, as his brooding throbbing pulsating highly engorged lips sought hers, not that she wanted to hold them back, we're talking about the waves of passion here, although she knew that somehow, somewhere, perhaps deep within the shuddering throes of yearninghood that even now gripped the very core of her womanhood, if you get what we mean, that she must find a way, through the hazy mists of desire, to end this sentence, although she sensed somehow that..."

Used in Flowers for Algernon in the sex scene between Charlie and Alice. It works, because it's used to show how different it is when he's with a woman he loves, than when he's just with a woman who enjoys sex.
Any nominee or winner of the Bad Sex in Fiction Award. An example of an especially amusing Talks Like a Simile passage: "Now her grubby soles met like they were praying. Now his skin was glazed in roast pork sweat. Now she made a noise like a tortured Moomintroll."
The one and (thankfully) only sex scene in Vurt by Jeff Noon is described entirely in a metaphor of a garden getting filled with sap. The best that can be said of it is that it's short.
The sex scenes between Claire and Adam in The Watermelon by Marian Keyes.
Fanny Hill: Memoirs of a Woman of Pleasure may be the Trope Maker.
Parodied in Anne Bishop's Tangled Webs, where Jaenelle is reading a bad romance novel and shows her husband a particularly purple passage. He responds, "Sweetheart, if my penis ever does that, you'll be the first to know. Not as my wife, but as a Healer."
The Fountainhead. Specifically, the rape scene.
Common in Danielle Steel's novels.

Live-Action TV

An early episode of Friends has Rachel attempt to write some ("Do you think his 'love stick' can be liberated from its 'denim prison'?"), inspired by Chandler's mother, who writes them professionally. Luckily for the broadcasters, she's a terrible speller so the others can openly mock her typos; the female character is apparently in possession of "heaving beasts", while the man at one point whips out his "huge throbbing pens".
- You don't wanna be around when he starts writing with those....
This is the favoured writing style of Garth Marenghi and Dean Learner:

Dean: I read modern writers, and it's "screw this", "he licked her", "she sucked that", "he bit the other", you know, "someone put it there", "he held it", you know, it was at this frequency. Where is the sensuality?
Garth: Yeah, where is "he glided in liquid smooth", where is "her wispy mound"?
Dean: Where's "her sacred V"?
Garth: "Her honeyed lining"?
Dean: "Her mossy cleft"?

Magazines

Mad Magazine suggested a Danielle Steel novelization of QVC:

A woman's hand (Was it hers?) now came into the screen. Lightly touching the bracelet at first, just the tips of the fingers. Slowly, the hand began a rhythmic stroking up and down the length of the brilliant, finely-crafted piece of jewelry. Giving the viewers an ever-rising desire to call and ensure that they could possess this thing of beauty.

Music

That Summer by Garth Brooks, especially the chorus, which would not at all be out of place in a romance novel:

She had a need to feel the thunder/To chase the lightning from the sky
To watch a storm with all its wonder/raging in her lover's eyes
She had to ride the heat of passion/like a comet burning bright
Rushing headlong in the wind/Out where only dreams have been
Burning both ends of the night.

Video Games

Nasuverse sex scenes are commonly a mild form of this (more so in Tsukihime than the later Fate/stay night). Oddly, they're also written in first-person perspective...

Web Comics

Jimbo's romance novels in Questionable Content.

Web Original

A fair amount of this, and plenty of other kinds of pornfail, shows up on weepingcock. An unofficial community motto is "there's a cream for that."
- Few things on that site could reach such heights of pretentious hilarity as the one guy referencing Ovid while taking advantage of a peach. Purple sex at its ~~worst~~ best.
Timely Extension of The Gift from Survival of the Fittest. The sex scene. My God.
CollegeHumor reinterprets college course texts as cheap bodice rippers.