I want to kidnap applejack and chain her up in my rape dungeon. She won't be able to move, and under her butt I will lay something precious to her...let's say her photo album of her family, open to irreplacable pictures and sacred about her fathers and such.

    Over two or three days I feed her regularly...but she gets very little water (she gets some, I'm not trying to kill her). I make her eat cheese and low-fiber sweets, so she gets constipated. If she gets stubborn and refuses to eat I might have to horsewhip her, but that's not really the point of this exercise
    Since her precious family photo album are right under her butt, and she can't move, she is unable to poop. She has to stand there as horrible pressure builds up against her rectum.

    After two or three days it's time for the harvest. I take the treasured family photo album away and move them to a safe place (I'm not a monster). Finally applejack is allowed to poop, and I collect it in a bucket. That's not enough though. With my bare ungloved hand I reach up her anus and scoop huge handfuls of poop out manually. For such little pony this is gonna hurt, so I might need some help holding her still.

    Finally, when all applejack's poop has been collected I portion it out into little bags and freeze it. Over the next few months I defrost 1 ounce baggies of applejack's poop in the microwave and use it as lubricant to fap with.
    Applejack can be released at this point. I give her a hug, some painkillers for her sore anus, and put her photo album in her saddleback. She can go to her home now

    I'll need some help with this plan. If you're interested I can pay you with a share of applejack's poop. If it goes well we can do it with some other pones.