"Okay, my turn to ask," Kate said. "Transform or Dare, Jen?"
"Transform. It's not like I can get any more freaky."
"We'll see," Kate squeeked. "For your transform, you'll shrink down to a foot tall. And, you'll grow a horse cock."
The curse took effect immediately and Jen felt a rush as everything suddenly got huge. In a matter of minutes, she was the same height as Kate and both were tiny. Then, she felt extreme ecstasy as her clit filled her pussy and quickly grow into a, had she still been human-sized, two-foot long horse dick. The horse's balls rapidly filled out beneath it.
"So, now what?" Jen asked. "I'm now a doll-sized, four-breasted freak with a horse's dick."
Kate just smiled, staring at what her sister had just grown.
"Fine," Jen said. "Your turn to get asked. Transform or dare, Kate?"
"Um," Kate stammered, trying to decide. "Let's see... I'm not sure."
It was Jen's turn to smile. "Your minute's up. You get both."
"Darn." Kate clearly didn't seem to mind that much.
"For your transform, let's make it simple. Your pussy will change into that of horse."
Both sisters watched as Kate's pussy expanded and puffed out until it had finished changing species.
"For your dare," Jen continued, "you'll grab your six-cupped bra that's hanging off the couch, lay it down here on the floor, and let me fuck you wild while laying in one of the cups."
"That sounds fun," Kate said, jogging over to the couch and dragging back the freaky bra.
The sisters climbed into one of the middle cups and went to town. They started on their knees, Jen drilling her sister like they were horses. Then Kate rolled over and spread her legs, Jen coming in from above. Finally, they switched places, and Kate rode her sister until both were sore.
They both flopped over on their backs and laughed.
"Man, that was fun," Jen said between breaths. "Maybe we need to have weird, kinky sex like this more often."
"Agreed," Kate replied, also breathing heavily.
"What now?" Jen asked.