Fan fic thread here: http://mlpforums.com/topic/93118-my-little-pony-bloopers/
Okay so this is more of me sharing the fan fic than me actually telling it due to the structure it's told in.
Okay, so every week after a new episode airs, me and my sister meet up on Skype to write this fan fic. It's basically what would happen if mlp wasn't voice acted but filmed on a Hollywood set. Think of it like a Who Framed Roger Rabbit style where the mane six are the actors and there are human directors and crew. The ponies film the show where the episodes are based on what actually happened in the show. It's one of those stories that's not meant to be taken seriously just a fun little idea. Also the fan fic is more of ideas and scenarios than a straightforward story. Also the running gag is that the ponies mess up their lines so badly, you wouldn't even think they read their scripts. I know I seem like I have trouble explaining this but here are just jokes out of the fan fic
Episode: Super Speedy Cider Squeezy 6000
Pinkie: DON'T WORRY RAINBOW DASH, I'LL GIVE YOU SOME OF MINE!
Director: CUT! You're not supposed to give her any cider
Pinkie: But, you gotta share, you gotta care.
Episode: Green isn't your color
Spike: I am a dragon
Director: CUT! You're supposed to say you have a crush on Rarity
Spike: BUT SHE'S RIGHT THERE!
Rarity: Uh yeah I already know, it's completely obvious
Episode: Filli Vanilli
Pinkie (picks up her script and reads it): Yeah I'm not saying any of this, that's mean.
Episode: Too many Pinkie Pies
Twilight: I found you Pinkie! You are defiantly the real Pinkie!
Director: CUT! You're supposed to find out through the watching paint dry idea
Twilight: But it's the one not acting stupid I didn't go to the school for gifted unicorns for nothing.
Episode: Over a Barrel
All: (coughing and choking due to too much dust)
Director: CUT! Too much dust effect
All right here's more I just remembered
Episode: Dragon Quest
Twilight, Rarity, and Rainbow Dash: (beat the crap out of the dragons)
Director: CUT! You were supposed to run away.
Twilight: But we can take them, I know magic, Rainbow Dash has kicked a bigger dragon in the face and Rarity looks like she's ready to attack.
Episode: Putting your hoof down.
Ponyville citizen: oh sorry Fluttershy didn't hear you I'll let you pass
Director: CUT! You're supposed to not care.
citizen: But she's Fluttershy and did you not see us sing the smile song where we advertise ourselves as nice ponies
Episode: Friendship is Magic part 2
The giggle at the ghosties song doesn't work
Mane six: AAAAAAAAHHHHHH!
Director: CUT! Nightmare Moon, your trees are supposed to disappear upon their laughter.
Nightmare Moon: Do you really think after all that time on the moon I would make trees that vulnerable?
Episode: The Ticket Master
Twilight: I give the ticket to Applejack!
Director: CUT! You're supposed to not give it to any of them.
Twilight: But Applejack has the most non selfish reason to go
Episode: Flight to the Finish
(scene where Diamond Tiara is bullying Scootaloo)
Rainbow Dash: (getting held back by 2 crew members) LET ME AT HER! LET ME AT HER!
Episode: It Ain't Easy Being Breezies
Twilight: (accidentally turns them into dragons
Rainbow Dash: ALL RIGHT!
Fluttershy: AAAAAHHHH! I'M SCARED OF MYSELF!
Twilight: Sorry this spell is hard.
Twilight: I can't get the spell right maybe they'll buy mane six dragons
Director: Sorry not cute enough for Hasbro to sell.
Spike: I am deeply offended!