It was a hot day - too hot. Even Celestia was starting to think it was perhaps just a little too warm, and she really likes the sun. For Big Mac, it was torture.
And he'd been out in the heat all day, making medium-distance deliveries to neighbouring settlements; settlements with names almost as imaginative as Ponyville, such as Colton, Manechester, and Horsetown.
So it was with a huge sense of relief that he arrived, finally, back at the Apple farm, late that Summer evening. Leaving the wagon in the barn, he trotted wearily round to the door of the farmhouse and stepped inside, relishing the cool of the flagstones beneath his hooves.
Then he splashed some cold water over his face, before popping into the larder and coming back with a large jug. Pouring himself a swift pint - of milk, not beer - he returned the jug to its place on the shelf, covered it with a teatowel to keep the flies away, and wandered comfortably through to the lounge.
Sighing pleasurably, he sank into an enormous armchair. He was just about to take a sip of the glass of milk he'd been carrying, when the door across the room, which led to the stairs and the rest of the house, creaked slowly open.
It was Applejack - but rather than coming through the doorway like a nice, normal pony, she simply stood within the doorframe, watching Big Mac with a vacant, unblinking stare.
"You 'kay, sis?" the stallion asked. "You look tired. . . d'you want some milk?"
At the word 'milk', Applejack leapt into action, lunging across the living room with such speed that a casual observer could almost be convinced she flew. "Nya!" she shrieked, landing in front of Big Mac with all the grace of an untrained, overtired ninja, and knocked the glass from his hoof, sending it, shattering, onto the floor. The milk seemed to go everywhere, leaving Big Mac, the armchair, the hearth and the rug liberally soaked.
"Now what was that for?" cried Big Mac, wiping milk from his eyes.
"Don't you let that - that - that thing near me!" his sister hissed, before falling back onto the sofa in a quivering heap.
After his initial shock, Big Mac was able to realise that, no matter how irrational her actions may have seemed, there would surely be a reason for them. And, seeing that she was now slowly rocking herself back and forth, eyes darting from side to side as though searching for a hidden enemy, he thought he'd better try and work out what it was. "What's wrong, AJ? What you got against milk?"
Again, her eyes widened in horror. "Don't you say that word!"
"What word - 'against'?"
"NO!" she shouted. "Don't you ever mention that word to me - that - the - the 'M' word!"
Puzzled, Big Mac thought for a moment. "Milk?" he inquired at last.
He knew he was right - because this time, Applejack leapt into the air like a startled cat on a hot, hot Saturday, and flung herself down to hide behind the sofa, landing with an uncomfortable-sounding thud.
Big Mac frowned. This sort of behaviour was not like his sister at all - or, rather, it was not like this sister at all. The other sister - what was her name again? - oh yeah, Applebloom - she could be a law unto herself, and did this sort of thing all the time.
He decided it was time to find out what was wrong. "Can you tell me why, AJ? Ah won't say the 'M' word again, Ah promise."
Peaking cautiously out from where she was hiding, Applejack swallowed, nervously, before clambering over the back of the sofa and sitting down, knees held up to protect her chest. "Ah s'ppose Ah could tell you," she announced.
"You see," she continued, "Ah was outside this morning, after you'd left to do the deliveries, and Ah thought Ah'd better - thought Ah'd better - better see to the cows."
Big Mac nodded - despite her refusal to use the word 'milk', he understood her perfectly. "Ah see. . . go on," he encouraged.
"Well, Ah was just - just seeing to the last cow, when it suddenly struck me."
She paused, eyes widening again, and Big Mac prodded her gently with his hoof, murmuring, "What struck you, sis?"
She snapped back to the present at his touch, and carried on. "Ah thought - Ah wonder what the cows think about all of this - y'know, the - the. . ."
She trailed off again, and seemed to be struggling with some internal battle. At last she gulped, and whispered, "Ah wondered what the cows thought about the milkin'."
She shuddered, rolling her shoulders subconsciously as though trying to rid them of some cloying evil which only she could sense. After a minute or two she was able to keep going. "Cos, y'see," she explained, "Ah've never really thought about that before. It all seems a bit - a bit private, if y'see what Ah'm saying. Y'know, it's like Ah'm fondling their - their - their boobs," she whispered, as though afraid Granny Smith, upstairs taking a nap, might overhear the borderline profanity and come and give her a whack with the ladle. "And Ah was like, why not just ask them?"
She fell silent again for a moment, and Big Mac waited patiently. Eventually, she carried on, saying, "So Ah said: 'Gloria,' - cos that was the cow's name, see, and Ah always call them by their names - 'Gloria, can Ah ask you somethin'?' And she said yes, so Ah did. Ah said, 'Y'know how Ah milk y'all, mornin' an' night'?' And she said yes. 'Well,' ah said, 'Are y'all sure y'all don't mind? Cos it seems a mighty private thing, touching a cow's boob like that'."
Applejack gulped, her breathing becoming shallower; Big Mac murmured gently, "It's alright, sis. You're safe. . ."
She nodded reluctantly, and continued. "Well, after Ah'd asked that, there was a pause, before she said something Ah won't never, ever unhear. She says to me, 'Oh, Applejack - you have such smooth hooves, and you're so gentle when you stroke us like that. . . how could we ever mind?' And then I realised it."
"Realised what?" encouraged Big Mac, leaning forward in his milk-stained armchair expectantly.
"Ah realised," cried Applejack, "That they enjoyed it! It felt like Ah was fondlin' their boobs cos that just what Ah was doin' - And they were getting off from it!"
Big Mac raised an interested eyebrow, and was about to say something, but Applejack hurried on; "So all these years Ah've been milking cows - Ah've been giving 'em orgasms! Orgasms, Big Mac! Like Ah'm some dirty, messed-up whore!"
"Ah see," murmured Big Mac. "And that bothers you?"
Almost speechless with incredulity at how calm her brother seemed to be, the disturbed Applejack cried, "Oh course it does! Ah can't go around giving creatures orgasms, not just like that! 'Tain't natural," she concluded, primly.
"So. . . that's put you off milk, then?" Big Mac inquired.
She nodded vigorously. "You bet it has, Big Mac. Ah ain't never touchin' a drop o' that - that - that liquid porn ever again! So don't you try and make me!"
Big Mac 'hushed', calmingly. "It's okay, sis," he soothed, "Ah won't make you. . ." After a moment's thought - though not enough thought, apparently - he added, "You want to go out for an ice-cream to help relax?"
Applejack shook her head rapidly, pupils mere pinpricks - before vomiting violently all over the floor.
Big Mac waited til she was done, and nodded. "Ah'll take that as a 'no', then."