Trollestia is one of the oldest memes in the fandom, dating back to the good ol days of /co/ before the MLPG's started. While it stands above most of the faggotry in this fandom, its still a forced meme and still witholds that status.
It all began when one /co/mrade pointed out on the third episode the ignorance of Celestia to give Twilight only two tickets to the Gala when she knew she had more than just two friends. This led to the suggestion of which she intentionally did it to troll, or if she didn't know that Ponyville was knowledgeable of the convention.
The recurring joke seemed to continue throughout the first season, but after "A Bird in the Hoof" it really jumped off. But in the end its just another advice pet variant, and the rest of the internet kind of got sick of those.