Cutie Mark Crusaders, Spell Testers!

Twilight perked up from her reading at the sound of a hoof tapping on wood and hopped out of her bed on the loft to answer it. The three young blank flanks were at the door, ready for another try at getting their cutie mark. “Thanks for coming to help me today girls! I have a brand new spell I’ve been working on that's just about ready for publishing! Only thing is it hasn't been tested on a foal yet."

“The pleasure’s ours Miss Sparkle!” Applebloom said with unbridled enthusiasm. Scootaloo and Sweetie Belle nodded and gave a playful salute.

“So what is it exactly we’re testing this time?” Sweetie asked with just a hint of derisiveness in her tone. Despite being a unicorn herself, she was a bit reluctant to do any magical favors for Twilight since the Want It, Need It incident. To her, magic was best used for simple levitation, like she and Rarity used around the boutique. Still, she wasn't one to miss out on an opportunity for a Cutie Mark.

A sly smirk spread across Twilight's face, and she blushed. "Well you see, it's not exactly a spell for foals, but of course we all know foals are gonna get their hands on it anyway. Normally there are some specially trained little ones the princesses can call on for this task but I assured Celestia I knew just the fillies, even if they lacked the training. Do you understand?" The trio nodded, eager as always to not only try earning their marks, but to show their maturity as well.

And so Twilight reared up on her hind hooves, balancing on two legs as best she could, and showed off the fruits of her laborious research. Below her petite breasts sat a package fit for a stallion. A deep, dark, plum color, the velvety skin of her sack was pulled tight around two egg-sized testes. Just above, a wrinkled sheath, shiny with sweat. The flat head of her shaft, along with a couple inches below it, were exposed as Twilight reveled in showing off but tried to restrain herself from letting it all out. Her cock was a slightly lighter purple than her sheath and balls, and a bead of precum had formed at the tip and was slowly sliding down the length. The Cutie Mark Crusaders looked on in amazement at the biological marvel before them, stunned by the prospect of getting ones of their own. Twilight's new additions jiggled as she struggled to steady herself, until she eventually lost her balance and fell back to the floor with a loud clack of her horseshoes, her balls thrust into a forward swing by the sudden motion. She gasped in a mixture of pleasure and pain as they slapped against her breasts, still not used to how much they swayed or how sensitive they were. She'd only activated the spell on herself the previous night, and after testing the goods a time or three, promptly passed out.

“So, who wants to go first?"