Celestia, Luna and Cadence have always been weird to Twilight.

Always making up phrases, and using words like boy when they meant colt.

Always making references to books and plays that never existed, and music that nopony has written.

For the longest time Twilight has been told it was nothing, just something Alicorns do.

Now at the start of the three day long secret holiday Canterlot Royal Summit she's going to find out.

Actual spoliers: <span class="spoiler">Different take on the whole Human in Equestria thing.</span>