I Was Having Such a Nice Dream

A character finds themselves in an important prophetic dream, receiving vital information from a dead relative in a near-death experience, or just having a terribly good time in their head, they hear the phone ringing or someone shouting their name and they are defibrillated back to the land of the living, just before the really good bit.

Anime and Manga
""And I was having... such a sweet dream.""
 * In the 8th episode of Azumanga Daioh, the "New Year's Dream Special", several of the main characters' dreams are shown. Schoolgirl Lesbian Kaorin naturally dreams about her crush, Sakaki, coming to her rescue, but the dream is interrupted by her mother trying to wake her up so they can take their traditional trip to the shrine on New Year's Day. Poor Kaorin just pulls the covers over her head and begs for it to keep going.
 * Discussed in Lucky Star episode 11. They rationalized why people who are unwilling to wake up specifically ask for five minutes, and not an hour.
 * Parodied in the first chapter of Chrono Crusade. Rosette is called on the phone to rush to a mission while her assistant, Chrono, is sleeping in their car. After the call she climbs into the car and tries to wake Chrono up--who protests that he needs to sleep "just a little longer". When Rosette asks how long, Chrono responds "about ten hours". Naturally, he gets punted out of the car and forced to go to work.
 * Later, Rosette refuses to wake up when Chrono shakes her repeatedly. So he tosses her out of an upper-story window. Azmaria is horrified, but he tells her there's a pond right under that window. Sure enough, Rosette comes back through the window, soaking wet, furious ... and with a fish flapping between her gritted teeth.
 * Hanaukyo Maid Tai. In episode 10 Taro's three maids try to wake him up at 5:00 in the morning. He asks for 1 more minute of sleep.
 * Done heartbreakingly in Tengen Toppa Gurren Lagann, when Viral realizes that

Film

 * At the end of Ice Age: The Meltdown, Scrat is in Fluffy Cloud Heaven, surrounded by all the acorns he could ever want, including one gigantic one. Before he can get at it, however, he is brought back to the living world when Sid gives him mouth to mouth. Needless to say, Scrat is not at all pleased.
 * In Star Trek VI: The Undiscovered Country, Kirk and McCoy were framed for murder and sent to a Klingon penal colony. They escape, and are trapped by the leader of the colony who arranged the murder, and is about to tell them who was responsible as he kills them. At that instant, based on the Viridian Patch that Spock had slapped on Kirk before they were sent into exile, they are beamed back to the Enterprise, just in time to save them from a certain death, but also making it impossible for them to find out the answer.

Literature
"Lionblaze: Aww, I was having a really great dream!
 * Randolph's Carter's motivation for undertaking The Dream-Quest of Unknown Kadath is to find again a glorious city he once saw in a dream but was snatched away from by the gods of Dream Land.
 * In The Order of the Phoenix, Harry Potter's prophetic dream is cut short by Ron's snoring, just as he was finally about to find out what was behind the mysterious door.
 * Happens a couple times in Warrior Cats:
 * Cats occasionally dream they were just about to catch a mouse when awakened.
 * During a drought, Lionblaze is dreaming about the lake being filled with water.

Cloudtail: And now you can go on a really great patrol."


 * In a dream, Squirrelpaw is talking to a spirit-cat, and is about to be told how she can save her sister, when Shrewpaw wakes her up.
 * is spying on the Dark Forest. She's just about to hear the plans for the final battle when awakens her.

Live Action TV

 * Subverted beautifully in Northern Exposure, "Spring Break". Joel remarks during his erotic dream of performing Robert Palmer's "Simply Irresistable" surrounded by the trademarked Palmer powerclones that he always wakes up before the good bit. One of the women leans over and tells him not this time -- the screen cuts to black and we hear a zipper being opened. Cue Titles.
 * One episode of Father Ted featured Ted in an Affectionate Parody of Ballykissangel, only without the Will They or Won't They between Father Peter and Assumpta; Ted and Assumpta definitely were, when he was woken by Father Dougal to offer him a peanut. Ted shouted at Dougal, went back to sleep, and had a nightmare where he was being chased by a giant peanut.
 * Hermans Head. Herman is woken up just as he does a swan dive onto a bed containing two beautiful women.
 * In The Nanny Fran is having the beginnings of an erotic dream about Maxwell, and she is woken by her mother. She goes back to sleep immediately afterwords. She later had to check if she was asleep, when Maxwell quoted the dream verbatim.

Newspaper Comics

 * A half-subversion can be found in an Outland strip. Opus is woken from a dream involving Aphrodite--yes, the Greek goddess Aphrodite--about to lick his nose in order to be told of some Washington scandal. He snarls at the person who did it, goes back to sleep--and finds that the key figure of the political scandal is now licking his nose.
 * In a Zits Sunday strip, Jeremy is recalling a bizarre dream he had (complete with visuals), which ended with his hot 4th grade teacher calling him over for something. The next panel shows an irritated Jeremy telling Hector that he wanted five extra minutes.

Western Animation

 * The South Park episode "Best Friends Forever" concerned a recently-deceased Kenny being enlisted by the forces of Heaven to defeat the forces of Hell, but he keeps being resuscitated at crucial moments.
 * Winx Club has a VERY special case: Tecna plays a partially-CG, partially-traditional animation sequence on her virtual goggles for her pixie Digit. It ends with her and boyfriend Timmy kissing. In the 4K dub, she's playing back a dream on her goggles, and it cuts right before the kiss, with a voice-over by Tec explaining that she woke up just before then. Screencap of the cut kiss, presented upside-down. And a video.

Real Life

 * Real-life example: According to popular legend, Samuel Taylor Coleridge's poem Kubla Khan was inspired by a dream he had. He was about halfway through writing the whole thing down when he was interrupted by a visitor -- and upon returning to his desk, could no longer remember the rest of his dream, forcing him to publish the (fairly sizeable) fragment he already had.
 * The other popular legend is that Coleridge wrote "Kubla Khan" in the midst of an opium high, and was interrupted by a knock at the door; having lost his train of thought, there was no getting it back. Ever.
 * Similarly, the story of Dr. Jekyll and Mr. Hyde came to author Robert Louis Stevenson in a dream. His wife, hearing his screams and assuming he was having a nightmare, awakened him, much to his incense. Apparently, she had awakened him at the first transformation scene.
 * Norm MacDonald worked this into an old stand-up bit about his dream of standing by a pool with Christie Brinkley, and waking up just before it gets to the good part. When he tries to re-dream the scenario, he winds up shooting pool with David Brinkley.
 * Composer Giuseppe Tartini had a dream where he sold his soul to the Devil; the Devil took up a violin and began to play a sonata Tartini described as "so wonderful and so beautiful, played with such great art and intelligence, as I had never even conceived in my boldest flights of fantasy." When he woke up, he jotted down as much as he could remember, calling it the Devil's Trill Sonata, but he still wrote that the difference between what he heard and what he wrote was so great that he would give up music forever just to recreate that one sonata.