It's been about two weeks or so since this specific episode aired, but I find it funny considering the OP.
Derpy Hooves.
A little backstory:
Let's go back to October 10, 2010. The day the first episode aired. The HUB, a then recently launched television network owned by Hasbro, aired the premiere of My Little Pony: Friendship is Magic on the day the network launched. Roughly 17 minutes into the premiere, there is a party being thrown in the main character, Twilight Sparkle's house. One of the ponies seen attending this party is a grey pegasus with a goofy, or "derpy" expression, blond hair, crossed eyes, and a cutie mark consisting of bubbles.
/co/, 4chan's Comics & Cartoons board, not long after, garnered many fans of the series, with a number of them dubbing this pony "Derpy Hooves," and a number of others theorizing that she is the pony responsible for delivering mail in Ponyville.
November 5, 2010
The fourth episode of My Little Pony: Friendship is Magic airs. In this episode, Applejack, one of the main cast, or "mane cast" as the fandom has dubbed her, at one point, volunteers to help another character bake muffins for Ponyville's ponies. She manages to, sleep deprived, no less, make a batch of muffins out of soda, potato chips, lemon juice, and earthworms. Long story short, they cause a mass food poisoning in Ponyville to everyone who eats them instead of Spike, Twilight Sparkle's assistant dragon.
Anywho, roughly 15 minutes in, Derpy Hooves is seen once more. A pony can be heard dreamily saying "Muffin..." and Derpy's lips are among three ponies that perfectly match to this word. The fandom dubs Derpy's favorite food to be muffins, because... do I need to say anything else?
Christmas Eve 2010
Episode 11 of the first season of My Little Pony: Friendship is Magic airs. In this episode, cleverly titled "Winter Wrap Up," the ponies of Ponyville have to wrap up winter (of course) and change the season manually to spring, accompanied with a catchy musical number. However, spring comes late every year, and one cause of this is that a pegasus named Ditzy Doo is mentioned to travel in the wrong direction to gather southern-bound birds. The fandom dubs, as an alternate name for Derpy, "Ditzy Doo." This was never confirmed as a canon name for Derpy, though Lauren Faust said that if she were to make Ditzy appear on screen, she would use Derpy's model.
February 11, 2011
Episode 15 of the first season of My Little Pony: Friendship is Magic airs. In this episode, Pinkie Pie, the bubbly, party-loving earth pony of the "mane cast" is shown to have an ability to physically predict the future, which is dubbed "Pinkie sense" in-universe. The aforementioned Twilight Sparkle attempts to scientifically debunk "Pinkie sense." At one point, she is examining Pinkie Pie in her natural habitat, and many things are dropped on her head from a delivery truck. One of the ponies seen delivering these fallen objects is nopony else but Derpy Hooves. She gives an awkward look to her coworker ponies before hiding her hooves behind her back.
The fandom squeals like the fangirls they are.
January 21, 2012
After many cameo appearances and plenty of fan speculation, Derpy Hooves is confirmed as a canon character by the MLP:FiM production staff.
It is on this day that the fourteenth episode of the second season of My Little Pony: Friendship is Magic airs. In the cold opening for this episode, Rainbow Dash, the tomboyish, athletic pegasus of the "mane cast," is fixing up Ponyville's city hall with a banner in hopes that the aforementioned Applejack would win a rodeo, which, supposedly, the Apple Family are known for. Assisting her is none other than Derpy Hooves. Derpy Hooves, in this scene, cannot do anything without somehow causing some form of damage. She bounces on a cloud, and it zaps both Rainbow Dash and herself. While casually flying whilst congratulating Rainbow Dash on her work, she knocks over the steeple of town hall, which Rainbow Dash fails to catch before landing in a hole deep within City Hall. Derpy asks if she can do anything to help before Rainbow Dash asks her to sit down and do absolutely nothing. She sits down, and the impact of her ass pounding down on the floor of City Hall causes her to fall down through a formed abyss. Derpy tries to hang on to Rainbow Dash in hopes of escaping, yet her efforts are futile and both of them fall to their non-fate. After a short departing speech from Applejack, Derpy gives a last-minute congratulation poking through the hole before falling back through.
It should be noted that Derpy is given speaking lines for this scene, and that the voice is somewhat akin to that of a mentally handicapped person. Tabitha St. Germain, who voiced Derpy for this scene and does regular voices for the show, including that of Rarity, another member of the mane cast, based this voice off of a boy related to somebody working in the studio.
One can only imagine what will next come of Derpy Hooves...
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Homework's whack, and so are rules.
Tuckin' in your shirt's for fools.