Sweetie Belle’s diaper pail opened with a soft click as Rarity’s hoof depressed and released the lid. Instantly the aroma of used diaper hit her nostrils, making her shiver at the naughtiness she was about to do. Inside the pail, several diapers rested, most only wet, but some discoloured by further use. Pushing aside the top few, Rarity took out her prize. A thick overnight diaper, heavily sodden and bulging with Sweetie’s mess.
 
As she pressed her muzzle into the diaper’s seat, inhaling the foul stench, she recalled back when, two days ago, she had changed her sister out of the filthy thing. Placing the balled-up diaper on the ground, she untaped it, the heavy front hitting the floor with a soft thud.  
The inside of the padding was completely brown, poop squished all the way up to the front waistband. She could even see the imprints her little sister’s cute flank had made in her mess. Rarity grinned, this was perfect. Gingerly, she lowered herself into Sweetie’s messy diaper, threading her tail through the hole. The cool mess smeared against her fur, eliciting a small gasp from her as the saturated padding released a little pee as it was squished.
 
Pulling up the front and taping herself into the used diaper, her marehood tingled as the soft poop pressed against it. Pressing a hoof into the padding, she let out a loud moan as the pleasure mounted…