Shaking Her Hair Loose

Imagine this picture: a woman with her hair tied up in a bun, held in place only with a pin or some kind of stick. She pulls it out of her hair and shakes it out, allowing it to fall down freely. This is sometimes accompanied by a Dramatic Wind.

This trope is usually either be part of a romantic scene or something dramatic, though it is also frequently parodied. The woman will usually be dressed up to the nines, and letting her hair out of its fancy updo is often the first step towards her undressing for her lover. A lot of the time this woman will have Rapunzel Hair, but the hair just needs to be long enough to tie up, so past the shoulders at the shortest.

Compare Letting Her Hair Down when a woman is shown wearing her hair down or looser to show how she's relaxing as a character, and Slipknot Ponytail when the hair gradually becomes undone on its own. Sometimes overlaps with Beautiful All Along. Could be seen as a sister trope to the Important Haircut without any actual hair cutting. If it's done for Fan Service then it'll usually be accompanied by a Hair Flip.

Examples of Shaking Her Hair Loose include:

Anime & Manga

Sophie of Last Exile is prim and proper with her hair tied up in a bun all the time. But when she is revealed to be the princess and returns to claim the throne she removes the bun and lets down her hair, resulting in a shift of behaviour as well.

Film -- Animated

Happens in Mulan at the end of the "Reflection" song where Mulan slowly removes all traces of the makeover she got for her meeting with the Matchmaker.
- Chi Fu also forcefully pulls her hair out of its bun when he reveals she is a woman.
In The Little Mermaid II: Return to the Sea, Ariel wears her hair tied up in a bun whenever she is on dry land, symbolizing how much more stern and strict she is. When Triton transforms her back into a mermaid, her hair comes undone and falls loose freely. After the ordeal is over, Ariel is shown wearing her hair down as a human to reflect her change in character.
Happens to Cinderella during the scene where the Fairy Godmother's magic spell is wearing off during the return trip from the ball.

Film -- Live Action

At the end of The Magdalene Sisters Bernadette sees two nuns watching her in the tunnel and, remembering when her hair was forcibly cut off, takes out the pin and shakes it loose before looking at them.
At the end of Twilight, we see Victoria watching Edward and Bella through a window, all dressed up. As she walks away she pulls a pin out of her hair and lets it fall to her waist.
In American Beauty when Jane strips for Ricky she unties her hair before taking off her bra and is more beautiful because of it.
In the Disney Channel movie Model Behaviour, Alex always wears her hair up in a tight bun held in place with two chopsticks. When she and Janine switch the first part of her transformation is shaking her hair out. This then gets inverted when Janine changes to Alex as she puts her hair up.
Parodied in Loaded Weapon 1 where a plain dowdy woman unties her hair and when she looks up she's played by a completely different actress.
A variation in Heartbreakers when Paige/Wendy is revealed to be Max's daughter she pulls off her red wig and shakes her natural brown hair loose.
In Mr. and Mrs. Smith Jane goes to see a mark pretending to be a prostitute with her hair pinned up. The first part of the seduction is shaking her hair out.
Lena in The Sisterhood of the Traveling Pants after she steps out to spend time with Kostas to show that she's now open to love.
Gen takes the Ice Princess, Casey, to a party without telling her where they were going. Gen tells her that it's okay that she's not dressed for a party as long as she shakes the hair loose.

Literature

In the poem The Highwayman, Bess the landlord's daughter leans out over the window and undoes her hair, allowing it to fall down so her lover can touch it.
Della from "The Gift of the Magi" is said to have hair right down to her waist but keeps it pinned up all the time. She lets it down dramatically just before it gets cut off to be sold.
Some versions of "Rapunzel" say that Rapunzel's long golden hair is braided 90% of the time, and it's only untied when Mother Gothel or the prince climb up it. The Disney version has Rapunzel's hair completely loose all the time, returning to being a braid only when she and Flynn briefly return to her home kingdom before Gothel captures her again.
Perenelle from The Alchemyst series is introduced with her hair tied back in a long plait. She shakes it loose whenever she performs magic.
In The Famine Secret, Fiona's long blonde hair is cut off when she enters the workhouse and when it grows longer she keeps it tied back so it won't get in the way. When she and her siblings escape the workhouse and go back to their home she unties her hair and allows the wind to blow it around her shoulders.

Live Action TV

In the Buffy the Vampire Slayer episode "Go Fish", Buffy pulls a stake out of her hair and shakes it loose as she prepares to fight a vampire.
Parodied in an episode of Tucker where Tucker imagines his parents getting together in a dramatic scene without dialogue. Jeannie first takes her hairclip out and shakes her hair loose before ripping off her waitress uniform to reveal a fancy dress underneath.
Another parody in an episode of Degrassi where Holly J shakes her hair out in a failed seduction attempt.
In one of Barney's Imagine Spots in an episode of How I Met Your Mother he seduces a female cop and she proceeds to shake her hair out of its bun and strip for him.
A quasi-parody happens in the Murder Mystery episode of Lizzie McGuire when Larry starts chatting up Veruca, both of them dressed in Edwardian era clothes. Veruca shakes her hair down as some faux dramatic music plays.
An episode of Friends has Ross and Monica's cousin Cassie shaking her hair loose in slow motion, prompting a sagging jaw from Chandler, Ross forgetting he's related to her and even Phoebe getting turned on.
In True Blood, Bill asks Sookie to take the clip out of her hair and shake it free before their first kiss.

Music

Rachel Steven's song "Some Girls" is about a woman attempting to seduce a man to get what she wants and one of the lines is "I'm gonna shake my hair out loose".

Professional Wrestling

Brooke Adams does this as part of her entrance in TNA, accompanied with dramatically removing her glasses and her coat.
When Michelle McCool had her sexy teacher gimmick she would sometimes come out with her hair in a bun and held in place with a pencil, only to pull it out and shake it loose when she started wrestling.
Similarly, Molly Holly in her WCW Miss Madness gimmick wore her blonde hair in a posh updo to fit her beauty pageant gimmick but when she wrestled she would dramatically undo her hair and shake it free.
Tamina once pulled her hair out its pigtails and shook it out before going to the top rope to deliver a Superfly Splash.

Webcomics

Near the end of Homestuck's Act 5, Part 2, the Handmaid lets her hair down right before strifing with Doc Scratch. This is because her primary weapons—a pair of wands—doubled as the pins holding her hair bun in place.

Western Animation

The Simpsons:
- Parodied in Marge's novel The Harpooned Heart; the book's heroine wears her hair under a bonnet but her lover pulls it off and lets it out. Since she has Marge's hairstyle, instead of falling down it shoots up.
- Played straight in "Last Tap Dance in Springfield" with Lisabella, the librarian.
- Parodied again with Comicbook Guy. When he's haggeling for some merchandise he offers to throw in his "man-scrunchie". Once removed, cue Sexophone and Slo-Mo Hair Flip.
In the Family Guy episode "Road to Rhode Island", Lois convinces Peter to watch some couples counseling with her, hosted by a mousy relationship doctor named Dr. Amanda Rebecca. After a few seconds, Dr. Rebecca asks the women to leave the room, as the next part only pertains to the men. When Lois departs, Dr. Rebecca tells Peter to "make sure your wife is out of the room" in a slightly more forceful tone. She then removes her glasses, shakes her hair bun loose in a dramatic (but sexy) fashion, starts speaking in a huskier voice (with her first line being "So, you wanna talk, or do you want me to take my top off?"), and gives Peter quite the eyeful with a striptease as a Sexophone plays. Her eyes even (in a rare Western Animation example) shift from Tareme Eyes to Tsurime Eyes. It turns out that these "relationship videos" are merely a front for Amanda to distribute pornographic videos of herself. Needless to say, Peter's on board with these videos.
In Sabrina the Animated Series the witches cast a spell on their strict new Nanny who wears her hair in a prim and proper bun. When the spell turns her into a hippie, she unties the bun and reveals she has long Rapunzel Hair.