"What?" I grinned at my cousin as I clutched her top to my new chest."What?" She smirked back.I shrugging, causing my cousin's hair to flit lightly across my breasts. "Why are you smiling?""Why are you smiling?"My cousin and I had found a magic stone that allowed us to swap bodies. We'd both enjoyed some alone time in our new forms and then she'd come into the bathroom as I was preparing to step into the shower. I was sort of self-conscious being naked in front of her but this was her body, so it wasn't like she hadn't seen it before.Also, she was naked in my body.I glanced down pointedly at her erection and then bit my lower lip. "You seem like you're enjoying being a guy. Do you want to…uh…" I trailed off, suddenly embarrassed to suggest it, though my new body was already becoming wonderfully warm."What?" She grinned, stepping closer until her cock brushed lightly against my thighs and the spicy scent of her sandalwood cologne tempted my nose.Our bodies fit together perfectly. Her hands were firm on my backside, pulling me in for a deep kiss as her manhood pressed urgently against my stomach. My pussy grew wet as she continued to caress me until finally she took me right there over the sink, both of us gaping down at our connection.as my former cock slid inside me, joining our warm wet heat as we crested together.

In Chapter 3 of this serial where Eric's mom has swapped their bodies to teach him a lesson, Eric's mom starts using him to fulfill her new body's desires. This is too taboo for Amazon and available only on Body Swap Stories and Smashwords.
https://bodyswapfiction.com/enter/?p=11657