Geddit? Because "caballo" is Spanish for horse, and these three are horses, and—okay, I'll stop killing it.
Anyway, I watched "The Three Caballeros" recently, and while that movie's freaking insane and I don't think that I'll be able to handle watching it again, I loved the characters of Jose Carioca and Panchito. And in my usual fashion, I started wondering if the three party ponies could play the Caballeros, and then drew this up.
Deciding which one was which was a little tricky—I don't blame you if you think that Cheese Sandwich should be Panchito (as it turns out, the rooster's a wanderer like Cheese is). But, it was ultimately Panchito's hyperactivity that made me decide that Pinkie Pie should play him, while Cheese, having been pretty chill half the time in "Pinkie Pride" (no really, he's mainly energetic in the musical numbers), plays the part of Jose, who while he's a party animal is noticeably more chill about it than his trigger happy friend.
And Party Favor's Donald because somepony had to play him. Plus, it kind of fits with the color schemes going on here. :XD:
Regardless, they're all loonatics and I love it.