It's a reference to when Fluttershy broke someone's spine for cutting in line.

"When somepony cuts in line, BREAK THEIR SPINE!"

The whole episode was about Fluttershy saying things like this. And since you either haven't seen the episode, mlp-fim.com/45

The WHOLE episode was about her being assertive like this. You clearly have either not seen it, or are not a brony. This is a Ponytime post. You have to be a brony to understand the jokes.

Yeah, I'm not watching that. Sorry, I've tried too many times to try and see why you guys enjoy the show, but I can't stand it. So me following that link is not going to happen.

If you can see it's a PONY post, you DON'T like ponies, then CLEARLY you WON'T get the reference. It isn't an "obscure reference" you just don't watch the show. Like how I am with Legend of Korra.
I don't watch the show, but I don't act like a stupid shit (you) because I don't understand a reference.

Resulting to name calling is the basis for retaliation my friend, I haven't disgraced you or tried to humiliate you in front of everybody so I would like the same level of fucking respect out of you.

I don't watch Legend of Korra either, but that show is apparently very entertaining because they seem to come up with a plethora of humorous content, excluding the obvious "in crowd" posts for people who watch the show, which is what most of your guys' content consists of. In which case, this post made a very small reference to the MLP show and was almost entirely unrelated aside from the "MFW you thumb" pictures.

Not everybody is part of the brony community, so please treat everybody with a certain level of understanding on their part.