Going up to the roof for some fresh air after pulling and all-nighter, our "hero" makes the mistake of closing his eyes for a bit.
When he opens them again, he is no longer on the rooftop in Copenhagen he was expecting to be on... no he's somewhere very different, and extremely unfamiliar.
How will he react? How will the ponies react? Nothing is certain, except for one thing...

He never asked for this.

This story takes place about 8'ish years after the second season of MLP:FiM, the language of Equestria does not match any earth languages (that the main character knows of at least), and the human in question knows nothing of these ponies or the world of Equestria.
He emerges into Equestria on the roof of a building in Manehattan, not the Everfree, not Ponyville and certainly not one of the princesses' bedrooms in Canterlot Castle.

Oh! Spoilers in the comments and all that jazz, not gonna go into a whole spiel about it.