Crazy Headcanons

Gilda dropped out of the flight academy and became a pro wrestler.

The ponies live in a post-apocalyptic Earth and all their technology and culture is scrounged from ruins of our civilization. That is why their civilization is so human-centric (Similar monuments, city names, music, etc).
 
Princess Celestia is actually G1 Surprise. She survived the cataclysm that destroyed humanity as a whole and threw the few surviving ponies into the dark ages, and created the elements of harmony to grant herself immortality so that she could watch over the world and never let such a tragedy ever happen again.
 
PIC <3 <3 <3  

When Big Mac is all alone in the orchards he likes to sing showtunes.
 
The reason there are royal nieces and nephews despite no evidence of Celesita or Luna ever having had children is due to politics. Rather than marry to form or bolster an alliance with foreign nations Celestia instead adopted ponies who weren’t likely to inherit their country’s thrones.
 
Samurai deer are a thing that exists.

Another one, the Equestria solar system was normal until Unicornia took control over it to have a lever against earth-ponies and pegasus. Celestia now control it alone to relieve the ponies of this burden but she can’t restore its normal revolution/rotation system as it was broken beyond repair.

@boz
 
That’s just crazy enough to be true. I like it.

Celestia and Luna don’t literally raise the sun and moon. The moon is in a locked orbit with the planet around the sun due to the presence of magic. The planet itself is being turned (with no inertial effects on the surface). Their planetary system (and world) were dying before magic was used to keep it going.

Princess Celestia (at least) is aware of other worlds, particularly ours. There’s a trade deal with Lauren Faust – concepts and stories for scientific information and a type of magical energy generated by attention. They’re going to be ticked off when they find out what Hasbro’s been changing!

King Sombra being the elder brother of Celestia and Luna and a fallen Alicorn (plus his cape could pobably be hiding massive scars caused by the loss of his wings or being an evil Alicorn from the start and his cape is hiding his wings).

Where to start: (I know… tldr)  
-Scootaloo is Cheerilee’s younger sister. Being raised in an Earth pony family would explain why she was never taught to fly.  
-Fluttershy had neglecting parents. This explains why when she fell nopony came to rescue her.  
-Rainbow Dash and Fluttershy have been dating ever since they met. This explains why they have been “close” friends.  
-Rarity is actually far older than the rest of the mane 6, but it makes her feel better to hang out with her friends.  
-Pinkie Pie’s family is Amish which is why she is no longer welcome to the farm. Her Aunt and Uncle are the Cakes and they welcome her to live with them.  
-King Sombra took the Crystal Empire by force.  
-Princess Celestia is hiding deep emotional trauma, as her friends, subjects, and servants pass away whereas she doesn’t.  
-Princess Cadence is Princess Celestia’s niece.  
-Prince Blueblood is not a Prince.  
-Derpy is a teenager (same as mane 6).  
-Daring Do is a real pony in their universe.  
-Lyra and Bonbon are a couple.  
-Caramel and Wind Whistler are a couple.  
-Blues has one eye with a weird black line around his head.  
-Star Swirl the Bearded is jealous of Twilight and becomes an antagonist.  
-Rainbow Dash’s mother disregarded her while her father gave her all of his attention. Her father raised her to be more of a tomboy.  
-Crystal ponies lost their crystal form as they left the crystal empire. Crystal ponies could have been around while the Empire was gone.  
-There are crystal unicorn and crystal pegasus ponies through breeding.  
-Applejack’s parents and grandfather are dead, but she toughs it out along with the rest of her family.  
-Applejack and Rarity are a new couple just after the season 3 premiere.  
-Trixie fell in love with Twilight Sparkle when she first saw her. This explains why Trixie pointed Twilight out from the rest of the crowd.  
-The CMC’s cutie marks are realizing they will be the CMC for the rest of their lives.  
-Pinkie is racist towards griffins. This explains her blaming Gustav first.  
-Dinky is Golden Harvest and Written Script’s daughter (people will most likely hate me for this). She is seen multiple times with Golden Harvest and Written Script together. The parents are also found to be always close to each other.

Twilight Sparkle is a reincarnation of Star Swirl the Bearded.

Humans exist in equestria but weren’t mentioned (or important) yet.
 
Humans are negatively magical causing magical creatures (including ponies) to percieve them as dark figures that darken their surroundings by their mere presence.  
They live in an enormous “wall city” that encompasses the entirety of equestria (think of the Chinese Great Wall but several times thicker and having houses/warehouses/granaries built in it) and protects it from evil magicks from the great magical wastelands beyond (or to be more exact the humans inhabiting it are passively doing the protecting).  
Their relations with ponies are usually borderline mistrust but they seem to have good relations with several earth pony settlements near the wall mostly due to earth ponies being hit the least by their aura.
 
Other ponies aren’t so lucky since unicorns become incapable of casting any but the most simple of spells (and trying to cast anytiong directly on a human is a fools errand) and pegasi usually temporarily lose their ability to fly and stand on clouds when near.  
Those unfortunate qualities usually mean that humans are not welcome in most equestrian towns.

Inside Pinkamena diane pie’s hair there is a macroscopic city that’s been stuck on to the surface of her scalp for years and since she was just a filly meaning it’s older than equestria and also she finds it very itchy too.

Prince Blueblood treated Rarity the way he did in part because he was friends with one of the Wonderbolts that Rarity kicked and nearly killed accidentally, and was getting back at her for it. He also has a severe allergy to strawberries, and used Rarity as a cake shield because he panicked, as the last time he got hit in the face with a cake, he was on triple strength antihistamines for a week.
 
Princess Luna had followers, but King Sombra destroyed most of them. In her rage, she dealt with Sombra’s army so brutally that the Elements of Harmony rejected her, meaning Celestia and Luna couldn’t just EOH him in the face when they confronted him. This turned into a destructive cycle that caused her to turn into Nightmare Moon. Her followers went with her to the dark side, albeit not all willingly, and after Luna was banished, they were forced into a nomadic lifestyle. Trixie is descended from these ponies.

Rainbow dash is afraid of water. That’s why she didn’t join Pinkie for a swim.

Princess Celestia hates snobby aristocrats to the point where she likes watching them get abused. She prefers the company of incredibly powerful usurpers willing to plunge Equestria into their own thematic brand of apocalypse than them. She’s emotionally abusive toward Prince Blueblood to the point where “I’m very disappointed in you” would be the nicest thing she’s said to him in 5 years. And that’s only because she stopped using sarcastic compliments around that time.
 
The nobles are onto this, and still act this way because they don’t give a crap about her opinions, calling them hypocritical.

Dinky is really a time traveler from the distant future who is stuck in Ponyville due to her machine malfunctioning and, because of it, wound up being turned into a filly.
 
Vinyl actually has a twin sister who mostly plays Hardstyle and Dubstep while she herself plays Techno and Electronica.
 
Another one is, Vinyl suffers from heterochromia and wears specially colored contact lenses because she doesn’t want other ponies to find out about it.

@EPPony  
>electronica
 
Urrrrgh, why must you enrage my inner genre-fag?

Diamond Tiara and Silver Spoon don’t hate Blank Flanks. Every interaction of them picking on a pony for being a Blank Flank has always been in relation to Apple Bloom, either her, her friends, or her family.
 
This is because Diamond Tiara and Apple Bloom used to be friends, but at some point, Apple Bloom almost killed Diamond Tiara, albeit by accident, but at the same time, it was due to her poor impulse control. Diamond Tiara because infuriated with Apple Bloom, but because Apple Bloom has a chronic inability to learn from these kinds of experiences, Diamond Tiara gave up on trying to convince Apple Bloom to stop being a reckless idiot, and now cares more about making Apple Bloom’s life miserable, the Blank Flank thing being her most effective means of doing so. Silver Spoon is in on the action because Apple Bloom nearly killed her best friend.

@Ebalosus  
My response was in reference to the timeline. If Star Swirl made them winged unicorns, that would require them to be around for the founding of Equestria because Star Swirl is from before the founding.
 
Anyway…
 
Sombra was actually Luna’s son. She wanted to deal with him herself instead of sending Twilight because she didn’t want to foist her family troubles on others.

@SpacePaladin  
This sounds crazy enough to work as a fanfic!

Equestria is a planet in the Segmentum Obscurus. The only thing standing between them and an all-out war with the Imperium of Man is that they have not yet been discovered.
 
Furthermore, if the Imperium happened upon Equestria, it would not be the sort of story to be told from the point of view of heroic guardsmen for the simple reason that they would lose.

I’ll drop some Sombra-related ones off.
 
Celestia and Luna initially struck King Sombra with the Elements of Harmony. It didn’t work, either because he embodies Fear as a form of Machiavellian Harmony or for some other reason. Turning him into shadow came later.
 
Sombra doesn’t look or act like any other pony because he’s a manifest nightmare created by Pre-NMM Luna; Sombra was her first attempt at shrouding the world in (metaphorical) darkness and showing the whole world how she felt (via the Crystal Heart). When Celestia found out what happened to the Crystal Empire she forced Luna to unmake Sombra and scolded her afterwards. Celestia still failed to see how Luna truly felt about their relationship, so Luna took it a step further by embracing the Nightmare.

King Sombra was once King Luz but got corrupted by the darkness.

Sombra was not native to Equestria nor the Crystal Empire. Curved horn, must be from a pony “Old World” if Equestria is situated in the “New World”.