Hair Reboot

A character whose potentially complicated hair is drenched, burnt, or otherwise misshaped merely has to shake their head to return it to the proper shape and volume. In extreme situations, this requires a 3 second combing.

Happens in live action, but usually done with a cut-away.

Contrast with Important Haircut, Expository Hairstyle Change, and Close-Call Haircut. Compare Reset Button but just for hair.

Not to be confused with re-writing the script for a famous '60s musical.

Examples of Hair Reboot include:

Anime and Manga

Gintoki in Gintama gets exploded in one of the later volumes (as if it only happens once), giving him a poofy afro. Sa-chan pleads with the writer to give him back his normal hair within a panel. Out of spite, perhaps, his hair stays that way for the next page.
Many a Close-Call Haircut in Dragonball Z has a Hair Reboot.
- Justified in that it's almost always Saiyan hair in question, which has different properties from human hair, supposedly. Either that, or it's Rule of Funny in action.
  - One particularly memorable (and grievous) example is in Movie 12, when Janemba manages to cut a huge chunk of Goku's hair off...and it's back within the next couple frames!
Parodied in Houshin Engi. Taikoubou and Suupuushan are shocked by an electric-based opponent, causing them to develop an afro and blonde curls, respectively. They stop in the middle of their fight to shampoo and blow-dry their hair back into its proper shape—in ancient China.
In Mahou Sensei Negima, the titular Negi has occasionally had his Hair Antennae sliced off in a Close-Call Haircut. It was back in the next panel.
- It seems Evangeline's immortality extends to her hair as well. When Secundum destroys a bit of her hair together with her arm, both arm and hair are restored to normal in no time.
Subverted by Hokuto no Ryu in Shaman King. The guy gets a Close-Call Haircut near the beginning of the series and his hair spends the rest of the story adopting more and more bizarre shapes as it slowly re-grows and gets cut again. It does not regain its original shape until very late in the story.
In Seto no Hanayome, the top of Nagasumi's head actually gets cut off. He's fine right afterward though.
Jessie from Pokemon tries to capture a Seviper in one episode. She does badly...until Seviper bites off a piece of her hair. After Jessie gives it a No-Holds-Barred Beatdown, her hair returns to normal in a few seconds.
Somewhat averted in Soul Eater—Black Star routinely gets his ridiculous main hair-spike cut in two, messed up or cut off. It generally stays that way for the length of the scene, but is always back to normal by the next episode at least.
A late episode of K-On!! has Yui accidentally chop her bangs very short while trying to trim them, and they go back to their usual length in the next episode. However, a bonus episode that chronologically took place shortly after this incident shows her with her hair still cut short.
In the official Doujinshi Anthology of Ace Attorney, main character Phoenix Wright (who is known for having had Anime hair ever since he was born, despite not using hairgel or the likes) is shown with wet hair in two instances, which reveals that he's literally an "Instant Bishounen, Just Add Water". How to get his hair back to it's usual shape? Shake his head twice and apply the hairdryer for aproximately two seconds. A very dumstruck Edgeworth compared it to "Shape Memory Alloy".
In Eureka Seven, Eureka lost a significant amount of hair in episode 19 and eventually has her hair grown back in an instant by Sakuya in episode 41. She even reverts back to her very original hairstyle by the final episode.
In Bleach, Tsukishima cuts off the majority of one of Riruka's very long pigtails in a Close-Call Haircut. The next time she is seen the entirety of the ponytail is back and in pristine condition.

Comic Books

This is a side effect of Wolverine's healing factor.

Film

The liquid-metal T-1000 gave itself a Hair Reboot in a scene late in Terminator II.
In Austin Powers in Goldmember Foxxy Cleopatra's hair goes from a fairly flat style from being wet to her full-out Funny Afro after she shakes her head.
Played for laughs in spoof spy movie OSS 117 Cairo Nest of Spies, where title character OSS 117 (a suave superspy played half Connery-era James Bond, half Inspector Clouzeau) wakes up with brushy head, then passes his hands in his hair, which is instantly and perfectly styled as a result.
Parodied in The Naked Gun, Frank Drebbin falls through a ceiling landing in a room full of thugs, dirty and hair messed up. As he stands, he idley puts his hands up to his head, as if to just brush a little of the dirt away. One jump cut later and he is totally clean and not a single hair is out of place.
Happens in The Little Mermaid. Ariel's hair manages to stay pretty much perfectly styled when she goes topside. Though she is a princess.
In the movie Bring It On, Kirsten Dunst's hair goes from wet to dry (and styled) very quickly during the carwash scene.
The Big Damn Movie of "Dragonball" had a scene of his hair gel only working a few seconds before it reverted too Anime Hair. Although drawing attention to it was hardly a good idea.
In Starcrash, simply thawing somebody from a deathlike state also styles her hair.

Literature

Harry Potter got this once as a kid overnight, as a result of a particularly bad haircut and accidental magic.

Live-Action TV

Avoided in Scrubs where JD shaves off his hair to show solidarity with a patient, but the next episode quickly skips to a month later when it's regrown, and does shown a number of flashback scenes of his time without it.
- Appears somewhat in a later series, where Dr. Cox has a mysteriously shaved head in 'My Night to Remember', only for his hair to be reset to normal in the next episode, three episodes before he eventually shaves his head onscreen in 'My Long Goodbye'.
In Out of Jimmy's Head the title character's hair sure stays perfectly neat in the movie despite having a brain transplant.
First lampshaded and then subverted in The Colbert Report; after Stephen Colbert got back from the USO shows in Iraq, he first wore an over-the-top fake wig and since has gotten increasingly blacker stubble.
In the Red Dwarf season 8 two-parter "Pete", Rimmer and Lister lose their hair while trying to cheat at spud duty. They get it back a few scenes later when Kryten uses a time digitizer. Note that this subplot is the least silly part of this episode.

Newspaper Comics

Get Fuzzy averted this when Rob accidentally used shampoo mixed with hair removal cream. His hair went from gone through stubby to normal length again in real time.

Video Games

In Devil May Cry 3, during the first fight with Vergil, it's raining and Vergil's normally spiked-back hairdo looks more like Dante's. After you, uh, "win", he makes a motion with his hand to slick back his hair with his hand and his hair goes back to normal.
In Jak & Daxter, Jak's Super Saiyan-esque antigravity hair flops down when he enters water (even if his head doesn't actually go below the surface) and immediately springs back up as soon as he leaves it.

Web Comic

Mocked in the webcomic Friendly Hostility. Fox has to shave his head and face after a lice outbreak at his job. His hair stays gone and takes a long while to grow back, but he realizes that his goatee grows back just the way it was within seconds of being removed. He spends a strip doing nothing but shaving his goatee off repeatedly, watching it grow back, and giggling like an electrocuted heron.
Lampshaded in Antihero for Hire. Shadehawk actually chooses his hairspray on the requirement that if he's suddenly drenched, it'll dry off instantly. Commercially-available Applied Phlebotinum at its finest.
Ozy and Millie had a Running Gag of every so often removing all of Ozy's (or, on rare occasion, Millie's) fur. After the shaving story arc, the following strips usually had a fully fluffy fox.
Averted in Air Force Blues, when Barbie's hair is removed entirely by the careful addition of hair removal cream to his shampoo. His hair grows back in real time but seems to stop once it reaches 'buzz cut' length. This is Lampshaded eventually after a trip to a secret airbase when it is revealed that he was a human guinea pig for an experiment.
The current page picture is one of the few times where Medium Awareness makes an appearance in Least I Could Do.

Western Animation

Johnny Bravo, from the series of the same name.
Happened a few times to Robin on Teen Titans, but a quick headshake fixed things.
An episode of Martin Mystery had Diana end up totally bald due to a bad dye job. By the next episode, her hair is back.
When Darkwing Duck gives himself an exaggerated corkscrew pompadour for a big date with Morganna McCawber, Morganna offers to "fix his part", then sweetly uses her magic to intentionally put his feathers right back to normal (after briefly turning him into a yak by accident).
This trope is parodied in an episode of Family Guy, when Peter's hair is shaved down to a mohawk. He says, "Good thing my hair is made out of Play-Doh." and squeezes out more hair like one of those Play-Doh crazy-hair toys, and styles it back to normal.
Avoided in King of the Hill, when Luanne's hair is burned off in a propane explosion: it gradually grows back over the next several episodes.
In an Amiga cartoon by Eric Schwartz, he has Amy the Squirrel come out of the shower and, after inspection in a mirror, simply whips her full bodied hair around to dry it and style it perfectly in less than 3 seconds. She then breaks the fourth wall to Lampshade Hanging it saying to the viewer, "Bet you wish your hair could do that!"
Averted in The Venture Brothers. Brock cut his hair short for his Rocky Horror costume in the season 1 finale, and he's still lacking his signature mullet in the season two premiere. His hair grows back over the next few episodes.
- Actually he was wearing a wig for the costume. He lost the mullet in a car explosion.
The Angry Beavers sometimes used this, but also plays around with it a little. In one episode, the beavers get shaved like poodles, and before heading out to get their revenge, Norbert dashes into the closet, comes out with his fur completely restored, and tosses Daggett a replacement fur coat for him, too. In another, Norbert gets repeatedly electrocuted, and every time he has less and less fur as a result, which stays like that throughout the episode.
Inverted in Total Drama Island, where Heather's hair is shaved at the end of the first season and she remains bald throughout the entire second season. This is unrealistic for the opposite reason: after several weeks pass, she really should have at least some hair again.
- Then again, she mentioned that her hair had been growing in, just "patchy and uneven". She probably re-shaved her head until the TDA special, where it's finally even.
In My Little Pony, during "The Glass Princess" story, a few of the ponies are captured and their manes are cut off. The hair grows back instantly, making the Mooks who cut it off goggle in amazement. (This was done because the writers were aware that the animators couldn't be relied on to draw the ponies with their manes cut for the rest of the serial.)
- Also occurs in My Little Pony Friendship Is Magic after Rarity chops off most of her tail. In this case, instead of growing back instantly, it only reverts to its normal length after invoking The Power Of Magic.
On Jimmy Two-Shoes, Jimmy gets his hair cut off thanks to a deadly rollercoaster Lucius had strapped him into. The next scene it was back.
Justified on The Fairly OddParents: After Timmy rips his hair out in frustration, his fairies poof it back on.
Happens to Jack Fenton from Danny Phantom: he had part of his hair ripped out by one of his ghost-hunting inventions in the first episode while his children were at school, but it was back to normal in the next scene he appeared, which was set during that same day in the early evening.
- Happens a few times to Danny due to how often he gets zapped. An offhand sweep of one hand is usually enough to get it back to its standard improbable spikes.
  - He lampshades this once, when his human form gets helmet hair. After he transforms, his hair spikes back to normal.

Danny: Well, at least the hair's better.

In Futurama, there's a robot you can call to make new hair when you lose yours.
Averted on The Powerpuff Girls with Sedusa. Her hair was cut off in "Something's a Ms." and it didn't grow back until 4 seasons later in "Aspirations" when she gathered some magical artifacts.