My fanon: Between the shape of the mouth and ears here, and Twilight, Applejack (who literally was raised in a barn), and Pinkie Pie (who ignores social property almost as often as the laws of physics) laying down on the counter, Starlight’s tail shape, and Rarity’s full-on transformation in sister images I shall choose to conclude that Discord played a minor prank by making the beverages at this cat-themed cafe make the drinker slightly look and/or act like a cat for a while after drinking…

In which case I suspect RD may be about to get “the rips”, which could prove rather destructive.