How Does Cum Work?

My stepsisters, Angel and Kitty, are always up to something. It’s constant experiments with them - they’ve always been partners in crime. I guess I never thought it was weird, but sometimes I swear I can hear them fucking around, rubbing their clits together and scissoring each other and all that. Pretty fucking weird, but I’ve always just stayed out of their business. That is, until one day, when they approached me about needing me for one of their projects. Turns out, they’re curious about how cum works, and more than anything in the world, they want a sample of it. I’m thinking, “There is no way this is actually happening, right?” But to my fucking surprise, my stepsisters get on their knees and start deepthroating my cock! Where did they learn to suck dick like this? And is it wrong for me to be enjoying it so much? Fuck, I never thought I’d be dick-deep in my stepsister’s throat, but here I am. I can’t help but feel like things are only going to get way, way more filthy between us now…